Antibodies to bone marrow stromal antigen 1

ABSTRACT

The invention provides antibodies which bind to the ADP-ribosyl cyclase 2. Nucleic acid molecules encoding the antibodies, expression vectors, host cells and methods for expressing the antibodies are also provided. The antibodies may be used for the treatment of human cancers, including acute myeloid leukemia (AML), B-cell chronic lymphocytic leukemia, breast cancer, colorectal cancer, kidney cancer, head and neck cancer, lung cancer, ovarian cancer and pancreatic cancer and human inflammatory diseases, including asthma, gout, crohns, lupus, multiple sclerosis, rheumatoid arthritis, psoriasis, diabetes and atherosclerotic.

RELATED APPLICATIONS

This application is a continuation-in-part of International ApplicationNo. PCT/US2012/044703, filed on Jun. 28, 2012, which claims priority toU.S. Provisional Application No. 61/502,167, filed on Jun. 28, 2011. Thecontents of the aforementioned applications are hereby incorporated byreference.

INTRODUCTION

The present disclosure relates generally to the fields of immunology andmolecular biology. More specifically, provided herein are antibodies andother therapeutic proteins directed against the ADP-ribosyl cyclase 2,nucleic acids encoding such antibodies and therapeutic proteins, methodsfor preparing monoclonal antibodies and other therapeutic proteins, andmethods for the treatment of diseases, such as cancers mediated by theADP-ribosyl cyclase 2 expression/activity and/or associated withabnormal expression/activity of ligands therefore.

BACKGROUND OF THE INVENTION

ADP-ribosyl cyclase 2 (also known as Bone marrow stromal antigen 1(BST1) or CD157) is a lipid-anchored, bi-functional ectoenzyme thatcatalyses ribonucleotide cyclisation and hydrolysis. It generates thenucleotide second messengers cyclic ADP-ribose and ADP-ribose that arecapable of activating calcium release and protein phosphorylation (FEBSLett. 1994, 356(2-3):244-8). It is able to support growth of pre-B cellsin a paracrine fashion, possibly through generation of NAD+ metabolites(Proc. Natl. Acad. Sci. USA 1994, 91:5325-5329; J Biol Chem. 2005,280:5343-5349).

ADP-ribosyl cyclase 2 and its homolog, CD38, appear to act as receptors,generating second messenger metabolites that induce intracellular Ca2+release via the ryanodine receptor (Biochem Biophys Res Commun. 1996,228(3):838-45). It may also act via CD11b integrin to effect Ca2+release through the PI-3 Kinase pathway (J Biol Regul Homeost Agents.2007; 21(1-2):5-11). BST1 has not been previously reported to originatefrom acute myeloid leukemia (AML), breast cancer, colorectal cancer,kidney cancer, lung cancer or pancreatic cancer cell membranes andrepresents a protein of new therapeutic and diagnostic value. BST1 isalso shown to be expressed on monocytes and granulocytes, both of whichcan be associated with and activated in diseases such as asthma, gout,crohns, lupus and diabetes. Monocytes are also implicated in thedevelopment of atherosclerotic plaques.

SUMMARY OF THE INVENTION

The present disclosure provides antibodies directed against the BST1,nucleic acids encoding such antibodies and therapeutic proteins, methodsfor preparing anti-BST1 antibodies and other therapeutic proteins, andmethods for the treatment of diseases, such as the BST1 mediateddisorders, e.g. human cancers, including acute myeloid leukemia (AML),B-cell chronic lymphocytic leukemia, breast cancer, colorectal cancer,kidney cancer, head and neck cancer, lung cancer, ovarian cancer,pancreatic cancer and human inflammatory diseases, including asthma,gout, crohns, lupus, multiple sclerosis, rheumatoid arthritis,psoriasis, diabetes and atherosclerotic, hereinafter referred to as ‘thediseases of the invention’.

Thus, the present disclosure provides isolated antibodies, in particularmurine, chimeric, humanized and fully-human monoclonal antibodies thatbind to the BST1 and exhibit one or more desirable functional property.Such properties include, for example, high affinity specific binding tothe BST1. Also provided are methods for treating a variety of theBST1-mediated diseases using the antibodies, proteins and compositionsof the present invention.

In one embodiment, the isolated anti-BST1 antibody possesses:

-   -   a) a heavy chain variable region comprising:    -   i) a first CDR comprising a sequence at least 80% identical to        SEQ ID NO: 10;    -   ii) a second CDR comprising a sequence at least 80% identical to        SEQ ID NO: 12 or SEQ ID NO: 51;    -   iii) a third CDR comprising a sequence at least 80% identical to        SEQ ID NO: 14; and    -   b) a light chain variable region comprising:    -   i) a first CDR comprising a sequence at least 80% identical to        SEQ ID NO: 16;    -   ii) a second CDR comprising a sequence at least 80% identical to        SEQ ID NO: 18;    -   iii) a third CDR comprising a sequence at least 80% identical to        SEQ ID NO: 20.

In a further embodiment, the isolated anti-BST1 antibody possesses:

-   -   a) a heavy chain variable region comprising:    -   i) a first CDR comprising a sequence at least 80% identical to        SEQ ID NO: 9;    -   ii) a second CDR comprising a sequence at least 80% identical to        SEQ ID NO: 11;    -   iii) a third CDR comprising a sequence at least 80% identical to        SEQ ID NO: 13; and    -   b) a light chain variable region comprising:    -   i) a first CDR comprising a sequence at least 80% identical to        SEQ ID NO: 15;    -   ii) a second CDR comprising a sequence at least 80% identical to        SEQ ID NO: 17;    -   iii) a third CDR comprising a sequence at least 80% identical to        SEQ ID NO: 19.

In a further embodiment, the isolated anti-BST1 antibody possesses:

-   -   a) a heavy chain variable region comprising:    -   i) a first CDR comprising a sequence at least 80% identical to        SEQ ID NO: 56;    -   ii) a second CDR comprising a sequence at least 80% identical to        SEQ ID NO: 57;    -   iii) a third CDR comprising a sequence at least 80% identical to        SEQ ID NO: 58; and    -   b) a light chain variable region comprising:    -   i) a first CDR comprising a sequence at least 80% identical to        SEQ ID NO: 59;    -   ii) a second CDR comprising a sequence at least 80% identical to        SEQ ID NO: 60;    -   iii) a third CDR comprising a sequence at least 80% identical to        SEQ ID NO: 61.

The epitope(s) recognized by the antibodies of the invention is foundwithin the polypeptide sequence of SEQ ID NO: 44.

In a further embodiment, the antibodies of the invention comprisevariable CDRs as compared to the parent antibodies described herein.Thus, the invention provides variant antibodies comprising variantvariable regions of a parent antibody, wherein the parent antibodycomprises a first vhCDR comprising SEQ ID NO:10, a second vhCDRcomprising a sequence selected from the group consisting of SEQ ID NO:12 and SEQ ID NO: 51, a third vhCDR comprising SEQ ID NO:14, a firstvlCDR comprising SEQ ID NO:16, a second vlCDR comprising SEQ ID NO: 18;and a third vlCDR comprising a SEQ ID NO:20, and wherein the variantantibody has 1, 2, 3, 4, 5 or 6 amino acid substitutions collectively inthe set of the first vhCDR, the second vhCDR, the third vhCDR, the firstvlCDR, the second vlCDR and the third vlCDR, with from 1 to 4substitutions of particular use, and wherein the antibody retainsspecific binding to BST1. Similarly, the parent antibody can comprise afirst vhCDR comprising SEQ ID NO:9, a second vhCDR comprising SEQ IDNO:11, a third vhCDR comprising SEQ ID NO:13; a first vlCDR comprisingSEQ ID NO:15, a second vlCDR comprising SEQ ID NO: 17 and a third vlCDRcomprising a SEQ ID NO:19. Furthermore, the parent antibody can comprisea first vhCDR comprising SEQ ID NO:56, a second vhCDR comprising SEQ IDNO: 57, a third vhCDR comprising SEQ ID NO:58, a first vlCDR comprisingSEQ ID NO:59, a second vlCDR comprising SEQ ID NO:60 and a third vlCDRcomprising a SEQ ID NO:61.

In a further embodiment, the isolated anti-BST1 antibody possesses theheavy chain variable region sequence as represented by SEQ ID NO: 2 andthe light chain variable region sequence as represented by SEQ ID NO: 4.

In another embodiment, the isolated anti-BST1 antibody possesses theheavy chain variable region sequence as represented by SEQ ID NO: 45 andthe light chain variable region sequence as represented by SEQ ID NO:49.

In another embodiment, the isolated anti-BST1 antibody possesses theheavy chain variable region sequence as represented by SEQ ID NO: 1 andthe light chain variable region sequence as represented by SEQ ID NO: 3.

In a further embodiment, the isolated anti-BST1 antibody possesses theheavy chain variable region sequence as represented by SEQ ID NO: 52 andthe light chain variable region sequence as represented by SEQ ID NO:53.

In one embodiment, any of the preceding antibodies possesses an Fcdomain. In some embodiments the Fc domain is human. In otherembodiments, the Fc domain is a variant human Fc domain.

In another embodiment, any of the preceding described antibodies aremonoclonal antibodies.

In one embodiment, any of the preceding described antibodies furtherpossesses a conjugated agent. In some embodiments the conjugated agentis a cytotoxic agent. In other embodiments the conjugated agent is apolymer. In another embodiment, the polymer is a polyethylene glycol(PEG). In another embodiment, the PEG is a PEG derivative.

In one embodiment, the isolated antibody is an antibody that competeswith any of the preceding antibodies for binding to BST1.

In another embodiment, a method for preparing any of the precedingantibodies is describe, the method being obtaining a host cell thatcontains one or more nucleic acid molecules encoding the precedingantibodies, growing the host cell in a host cell culture, providing hostcell culture conditions wherein the one or more nucleic acid moleculesare expressed, and recovering the antibody from the host cell or thehost cell culture.

In one embodiment, any of the described anti-BST1 antibodies is providedin a pharmaceutical composition.

In another embodiment, a method for treating or preventing a diseaseassociated with BST1, the method being administering to a subject inneed thereof any of the preceding antibodies in an effective amount.

The present invention provides an isolated monoclonal antibody, or anantigen-binding portion thereof, an antibody fragment, or an antibodymimetic which binds an epitope on the human BST1 recognized by anantibody comprising a heavy chain variable region comprising an aminoacid sequence set forth in a SEQ ID NO: selected from the groupconsisting of 2, 1 and 52 and a light chain variable region comprisingan amino acid sequence set forth in a SEQ ID NO: selected from the groupconsisting of 4, 3 54 and 55. In some embodiments the isolated antibodyis a full-length antibody of an IgG1, IgG2, IgG3, or IgG4 isotype.

In some embodiments, the antibody of the present invention is selectedfrom the group consisting of: a whole antibody, an antibody fragment, ahumanized antibody, a single chain antibody, an immunoconjugate, adefucosylated antibody, and a bispecific antibody. The antibody fragmentmay be selected from the group consisting of: a Unibody®, a domainantibody and a Nanobody®. In some embodiments, the immunoconjugates ofthe invention comprise a therapeutic agent. In another aspect of theinvention, the therapeutic agent is a cytotoxin or a radioactiveisotope.

In some embodiments, the antibody of the present invention is selectedfrom the group consisting of: an Affibody®, a DARPin®, an Anticalin®, anAvimer®, a Versabody® and a Duocalin®.

In alternative embodiments, compositions of the present inventioncomprise an isolated antibody or antigen-binding portion and apharmaceutically acceptable carrier.

In other aspects, the antibody of the present invention is a compositioncomprising the isolated antibody or antigen-binding portion according tothe invention and a pharmaceutically acceptable carrier.

In some embodiments, the invention comprises an isolated nucleic acidmolecule encoding the heavy or light chain of the isolated antibody orantigen-binding portion which binds to an epitope on the human BST1.Other aspects of the invention comprise expression vectors comprisingsuch nucleic acid molecules, and host cells comprising such expressionvectors.

In some embodiments, the present invention provides a method forpreparing an anti-BST1 antibody, said method comprising the steps of:obtaining a host cell that contains one or more nucleic acid moleculesencoding the antibody of the invention; growing the host cell in a hostcell culture; providing host cell culture conditions wherein the one ormore nucleic acid molecules are expressed; and recovering the antibodyfrom the host cell or from the host cell culture.

In other embodiments, the invention is directed to methods for treatingor preventing a disease associated with target cells expressing theBST1, said method comprising the step of administering to a subject ananti-BST1 antibody, or antigen-binding portion thereof, in an amounteffective to treat or prevent the disease. In some aspects, the diseasetreated or prevented by the antibodies or antigen-binding portionthereof of the invention, is human cancer. In some embodiments, thediseases treated or prevented by the antibodies of the present inventioninclude the diseases of the invention.

In other embodiments, the invention is directed to methods for treatingor preventing a disease associated with target cells expressing theBST1, said method comprising the step of administering to a subject ananti-BST1 antibody, or antigen-binding portion thereof, in an amounteffective to treat or prevent the disease. In some aspects, the diseasetreated or prevented by the antibodies or antigen-binding portionthereof of the invention, is human cancer. In some embodiments, thediseases treated or prevented by the antibodies of the present inventionare the diseases of the invention.

In other embodiments, the invention is directed to an anti-BST1antibody, or antigen-binding portion thereof, for use in treating orpreventing a disease associated with target cells expressing the BST1.In some aspects, the disease treated or prevented by the antibodies orantigen-binding portion thereof of the invention is human cancer. Insome embodiments, the diseases treated or prevented by the antibodies ofthe present invention are the diseases of the invention.

In other embodiments, the invention is directed to the use of ananti-BST1 antibody, or antigen-binding portion thereof, for themanufacture of a medicament for use in treating or preventing a diseaseassociated with target cells expressing the BST1. In some aspects, thedisease treated or prevented by the medicament of the invention is humancancer. In some embodiments, the diseases treated or prevented by themedicament of the present invention are the diseases of the invention.

In other embodiments, the present invention is an isolated monoclonalantibody or an antigen binding portion thereof, an antibody fragment, oran antibody mimetic which binds an epitope on the human BST1 recognizedby an antibody comprising a heavy chain variable region and a lightchain variable region selected from the group consisting of the heavychain variable region amino acid sequence set forth in SEQ ID NO: 2 andthe light chain variable region amino acid sequence set forth in SEQ IDNO: 4; heavy chain variable region amino acid sequence set forth in SEQID NO: 1 and the light chain variable region amino acid sequence setforth in SEQ ID NO: 3; heavy chain variable region amino acid sequenceset forth in SEQ ID NO: 52 and the light chain variable region aminoacid sequence set forth in SEQ ID NO: 53. In further aspects, theantibody is selected from the group consisting of: a whole antibody, anantibody fragment, a humanized antibody, a single chain antibody, animmunoconjugate, a defucosylated antibody, and a bispecific antibody. Infurther aspects of the invention, the antibody fragment is selected fromthe group consisting of: a Unibody®, a domain antibody, and a Nanobody®.In some embodiments, the antibody mimetic is selected from the groupconsisting of: an Affibody®, a DARPin®, an Anticalin®, an Avimer®, aVersabody®, and a Duocalin®. In further embodiments, the compositioncomprises the isolated antibody or antigen binding portion thereof and apharmaceutically acceptable carrier.

In some embodiments, the present invention is an isolated nucleic acidmolecule encoding the heavy or light chain of the isolated antibody orantigen binding portion thereof of antibody of the invention, and infurther aspects may include an expression vector comprising such nucleicacids, and host cells comprising such expression vectors.

Another embodiment of the present invention is a hybridoma expressingthe antibody or antigen binding portion thereof of any one of antibodiesof the invention.

Other aspects of the invention are directed to methods of making theantibodies of the invention, comprising the steps of:

-   -   immunizing an animal with an BST1 peptide;    -   recovering mRNA from the B cells of said animal;    -   converting said mRNA to cDNA;    -   expressing said cDNA in phages such that anti-BST1 antibodies        encoded by said cDNA are presented on the surface of said        phages;    -   selecting phages that present anti-BST1 antibodies;    -   recovering nucleic acid molecules from said selected phages that        encode said anti-BST1 immunoglobulins;    -   expressing said recovered nucleic acid molecules in a host cell;        and    -   recovering antibodies from said host cell that bind to the BST1.

In some aspects of the invention, the isolated monoclonal antibody, oran antigen binding portion thereof, binds an epitope on the BST1polypeptide having an amino acid sequence of SEQ ID NO: 44 recognized byan antibody comprising a heavy chain variable region comprising an aminoacid sequence set forth in a SEQ ID NO: selected from the groupconsisting of 2, 1 or 52, and a light chain variable region comprisingan amino acid sequence set forth in a SEQ ID NO: selected from the groupconsisting of 4, 3 or 53.

Other features and advantages of the instant invention will be apparentfrom the following detailed description and examples which should not beconstrued as limiting. The contents of all references, Genbank entries,patents and published patent applications cited throughout thisapplication are expressly incorporated herein by reference.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A shows the alignment of the nucleotide sequences of the heavychain CDR1 regions of A1 (SEQ ID NO:21) with nucleotides 138392-138424of the mouse germline V_(H) 1-80 nucleotide sequence (SEQ ID NO:33); thealignment of the nucleotide sequences of the heavy chain CDR1 regions ofA2 (SEQ ID NO:22) with nucleotides 153362-153394 of the mouse germlineV_(H) 1-39 nucleotide sequence (SEQ ID NO:35).

FIG. 1B shows the alignment of the nucleotide sequences of the heavychain CDR2 regions of A1 (SEQ ID NO:23) with nucleotides 138461-138511of the mouse germline V_(H) 1-80 nucleotide sequence (SEQ ID NO:34); thealignment of the nucleotide sequences of the heavy chain CDR2 regions ofA2 (SEQ ID NO:24) with nucleotides 153431-153481 of the mouse germlineV_(H) 1-39 nucleotide sequence (SEQ ID NO:36).

FIG. 2A shows the alignment of the nucleotide sequences of the lightchain CDR1 regions of A1 (SEQ ID NO:27) with nucleotides 496-531 of themouse germline V_(K) 4-74 nucleotide sequence (SEQ ID NO:37); thealignment of the nucleotide sequences of the light chain CDR1 regions ofA2 (SEQ ID NO:28) with nucleotides 523-552 of the mouse germline V_(K)4-55 nucleotide sequence (SEQ ID NO:40).

FIG. 2B shows the alignment of the nucleotide sequences of the lightchain CDR2 regions of A1 (SEQ ID NO:29) with nucleotides 577-597 of themouse germline V_(K) 4-74 nucleotide sequence (SEQ ID NO:38); thealignment of the nucleotide sequences of the light chain CDR2 regions ofA2 (SEQ ID NO:30) with nucleotides 598-618 of the mouse germline V_(K)4-55 nucleotide sequence (SEQ ID NO:41).

FIG. 2C shows the alignment of the nucleotide sequences of the lightchain CDR3 regions of A1 (SEQ ID NO:31) with nucleotides 691-718 of themouse germline V_(K) 4-74 nucleotide sequence (SEQ ID NO:39); thealignment of the nucleotide sequences of the light chain CDR3 regions ofA2 (SEQ ID NO:32) with nucleotides 715-739 of the mouse germline V_(K)4-55 nucleotide sequence (SEQ ID NO:42).

FIGS. 3A and 3B show results of flow cytometric analysis of BST1 on A549and H226 cells.

FIGS. 4A and 4B show the internalization of anti-BST1 monoclonalantibodies by A549 and H226 cells, using MabZAP assay.

FIG. 5 shows the alignment of residues 21-137 of SEQ ID NO: 2 (SEQ IDNO: 45), humanized VH chain with the CDR regions (highlighted in bold)of SEQ ID NO: 2 transferred to the corresponding positions of the humangermline BF238102 VH (SEQ ID NO: 46), with human germline BF238102 VH(SEQ ID NO: 47). Residues showing significant contact with CDR regionssubstituted for the corresponding human residues. These substitutions(underlined) were performed at positions 30, 48, 67, 71 and 100.

FIG. 6 shows the alignment of residues 22-128 of SEQ ID NO: 4 (SEQ IDNO: 48), humanized VL chain with the CDR regions (highlighted in bold)of SEQ ID NO: 4 transferred to the corresponding positions of the humangermline X72441 VL (SEQ ID NO: 49) with human germline X72441 VL (SEQ IDNO: 50). Residues showing significant contact with CDR regionssubstituted for the corresponding human residues. One substitution(underlined) was performed at position 71.

FIG. 7 shows the alignment of CDR2 region of A2 heavy chain (SEQ ID NO:12) with possible amino acid substitutions (SEQ ID NO: 51) withoutlosing the antigen-binding affinity.

FIGS. 8A and 8B show BST1_A2 and BST1_A2_NF eliciting an antibodydependent cellular cytotoxicity (ADCC) response in the presence ofeffector cells.

FIG. 9A depicts BST1_A2_NF eliciting an antibody dependent cellularcytotoxicity (ADCC) response against U937 cells in the presence of NKcells isolated from patients with AML and healthy donors.

FIG. 9B depicts Rituximab eliciting an antibody dependent cellularcytotoxicity (ADCC) response against RAJI cells in the presence of NKcells isolated from patients with AML and healthy donors.

FIG. 10 depicts BST1_A2_NF eliciting an antibody dependent cellularcytotoxicity (ADCC) response against monocytes cells in the presence ofeffector cells.

FIG. 11A depicts results of flow cytometric analysis of BST1_A2_NF onBST1 cynomolgus monkey antigen-transfected HEK 293FS cells.

FIG. 11B depicts results of flow cytometric analysis of variousconcentrations of BST1_A2_NF on BST1 cynomolgus monkeyantigen-transfected HEK 293FS cells.

FIG. 12A depicts the TK profile of BST1_A2_NF after IV infusion for thefirst dosing in an exploratory toxicity study in cynomolgus monkeys.

FIG. 12B depicts the TK profile of BST1_A2_NF after IV infusion for thesecond dosing in an exploratory toxicity study in cynomolgus monkeys.

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure relates to isolated antibodies, including, butnot limited to monoclonal antibodies, for example, which bindspecifically to the BST1 with high affinity as outlined herein. Incertain embodiments, the antibodies provided possess particularstructural features such as CDR regions with particular amino acidsequences. This disclosure provides isolated antibodies (which, asoutlined below, includes a wide variety of well known structures,derivatives, mimetics and conjugates) methods of making said molecules,and pharmaceutical compositions comprising said molecules and apharmaceutical carrier. This disclosure also relates to methods of usingthe molecules, such as to detect the BST1, as well as to treat diseasesassociated with expression of the BST1, such as the BST1 expressed ontumors and inflammatory diseases, including the diseases of theinvention.

In order that the present disclosure may be more readily understood,certain terms are first defined. Additional definitions are set forththroughout the detailed description.

Humanized and murine antibodies of this disclosure may, in certaincases, cross-react with the BST1 from species other than human. Incertain embodiments, the antibodies may be completely specific for oneor more human BST1 and may not exhibit species or other types ofnon-human cross-reactivity.

The term “immune response” refers to the action of, for example,lymphocytes, antigen presenting cells, phagocytic cells, granulocytes,and soluble macromolecules produced by the above cells or the liver(including antibodies, cytokines, and complement) that results inselective damage to, destruction of, or elimination from the human bodyof invading pathogens, cells or tissues infected with pathogens,cancerous cells, or, in cases of autoimmunity or pathologicalinflammation, normal human cells or tissues.

A “signal transduction pathway” refers to the biochemical relationshipbetween various signal transduction molecules that play a role in thetransmission of a signal from one portion of a cell to another portionof a cell. As used herein, the phrase “cell surface receptor” includes,for example, molecules and complexes of molecules capable of receiving asignal and the transmission of such a signal across the plasma membraneof a cell. An example of a “cell surface receptor” is the BST1.

The term “antibody” as referred to herein includes, at a minimum, anantigen binding fragment (i.e. “antigen-binding portion”) of animmunoglobulin.

The definition of “antibody” includes, but is not limited to, fulllength antibodies, antibody fragments, single chain antibodies,bispecific antibodies, minibodies, domain antibodies, syntheticantibodies (sometimes referred to herein as “antibody mimetics”),chimeric antibodies, humanized antibodies, antibody fusions (sometimesreferred to as “antibody conjugates”) and fragments and/or derivativesof each, respectively. In general, a full length antibody (sometimesreferred to herein as “whole antibodies”) refers to a glycoprotein whichmay comprise at least two heavy (H) chains and two light (L) chainsinter-connected by disulfide bonds. Each heavy chain is comprised of aheavy chain variable region (abbreviated herein as V_(H)) and a heavychain constant region. The heavy chain constant region is comprised ofthree domains, C_(H)1, C_(H)2 and C_(H)3. Each light chain is comprisedof a light chain variable region (abbreviated herein as V_(L) or V_(K))and a light chain constant region. The light chain constant region iscomprised of one domain, C_(L). The V_(H) and V_(L)/V_(K) regions can befurther subdivided into regions of hypervariability, termedcomplementarity determining regions (CDR), interspersed with regionsthat are more conserved, termed framework regions (FR). Each V_(H) andV_(L)/V_(K) is composed of three CDRs and four FRs, arranged fromamino-terminus to carboxy-terminus in the following order: FR1, CDR1,FR2, CDR2, FR3, CDR3, FR4. The variable regions of the heavy and lightchains contain a binding domain that interacts with an antigen. Theconstant regions of the antibodies may mediate the binding of theimmunoglobulin to host tissues or factors, including various cells ofthe immune system (e.g. effector cells) and the first component (Clq) ofthe classical complement system.

In one embodiment, the antibody is an antibody fragment. Specificantibody fragments include, but are not limited to, (i) the Fab fragmentconsisting of V_(L), V_(H), C_(L) and C_(H)1 domains, (ii) the Fdfragment consisting of the V_(H) and C_(H)1 domains, (iii) the Fvfragment consisting of the V_(L) and V_(H) domains of a single antibody,(iv) the dAb fragment, which consists of a single variable domain, (v)isolated CDR regions, (vi) F(ab′)2 fragments, a bivalent fragmentcomprising two linked Fab fragments (vii) single chain Fv molecules(scFv), wherein a V_(H) domain and a V_(L) domain are linked by apeptide linker which allows the two domains to associate to form anantigen binding site, (viii) bispecific single chain Fv dimers, and (ix)“diabodies” or “triabodies”, multivalent or multispecific fragmentsconstructed by gene fusion. The antibody fragments may be modified. Forexample, the molecules may be stabilized by the incorporation ofdisulfide bridges linking the V_(H) and V_(L) domains. Examples ofantibody formats and architectures are described in Holliger & Hudson(2006) Nature Biotechnology 23(9):1126-1136, and Carter (2006) NatureReviews Immunology 6:343-357, and references cited therein, allexpressly incorporated by reference.

The present disclosure provides antibody analogs. Such analogs maycomprise a variety of structures, including, but not limited to fulllength antibodies, antibody fragments, bispecific antibodies,minibodies, domain antibodies, synthetic antibodies (sometimes referredto herein as “antibody mimetics”), antibody fusions, antibodyconjugates, and fragments of each, respectively.

In one embodiment, the immunogloublin comprises an antibody fragment.Specific antibody fragments include, but are not limited to (i) the Fabfragment consisting of VL, VH, CL and CH1 domains, (ii) the Fd fragmentconsisting of the VH and CH1 domains, (iii) the Fv fragment consistingof the VL and VH domains of a single antibody; (iv) the dAb fragment,which consists of a single variable, (v) isolated CDR regions, (vi)F(ab′)2 fragments, a bivalent fragment comprising two linked Fabfragments (vii) single chain Fv molecules (scFv), wherein a VH domainand a VL domain are linked by a peptide linker which allows the twodomains to associate to form an antigen binding site, (viii) bispecificsingle chain Fv dimers, and (ix) “diabodies” or “triabodies”,multivalent or multispecific fragments constructed by gene fusion. Theantibody fragments may be modified. For example, the molecules may bestabilized by the incorporation of disulphide bridges linking the VH andVL domains. Examples of antibody formats and architectures are describedin Holliger & Hudson, 2006, Nature Biotechnology 23(9):1126-1136, andCarter 2006, Nature Reviews Immunology 6:343-357 and references citedtherein, all expressly incorporated by reference.

The recognized immunoglobulin genes, for example in humans, include thekappa (κ), lambda (λ), and heavy chain genetic loci, which togethercomprise the myriad variable region genes, and the constant region genesmu (υ), delta (δ), gamma (γ), sigma (σ), and alpha (α) which encode theIgM, IgD, IgG (IgG1, IgG2, IgG3, and IgG4), IgE, and IgA (IgA1 and IgA2)isotypes respectively. Antibody herein is meant to include full lengthantibodies and antibody fragments, and may refer to a natural antibodyfrom any organism, an engineered antibody, or an antibody generatedrecombinantly for experimental, therapeutic, or other purposes.

In one embodiment, an antibody disclosed herein may be a multispecificantibody, and notably a bispecific antibody, also sometimes referred toas “diabodies”. These are antibodies that bind to two (or more)different antigens. Diabodies can be manufactured in a variety of waysknown in the art, e.g. prepared chemically or from hybrid hybridomas. Inone embodiment, the antibody is a minibody. Minibodies are minimizedantibody-like proteins comprising a scFv joined to a C_(H)3 domain. Insome cases, the scFv can be joined to the Fc region, and may includesome or all of the hinge regions. For a description of multispecificantibodies, see Holliger and Hudson (2006) Nature Biotechnology23(9):1126-1136 and references cited therein, all expressly incorporatedby reference.

By “CDR” as used herein is meant a “complementarity determining region”of an antibody variable domain. Systematic identification of residuesincluded in the CDRs have been developed by Kabat (Kabat et al. (1991)Sequences of Proteins of Immunological Interest, 5th Ed., United StatesPublic Health Service, National Institutes of Health, Bethesda) andalternately by Chothia [Chothia and Lesk (1987) J. Mol. Biol. 196:901-917; Chothia et al. (1989) Nature 342: 877-883; Al-Lazikani et al.(1997) J. Mol. Biol. 273: 927-948]. For the purposes of the presentinvention, CDRs are defined as a slightly smaller set of residues thanthe CDRs defined by Chothia. V_(L) CDRs are herein defined to includeresidues at positions 27-32 (CDR1), 50-56 (CDR2), and 91-97 (CDR3),wherein the numbering is according to Chothia. Because the V_(L) CDRs asdefined by Chothia and Kabat are identical, the numbering of these V_(L)CDR positions is also according to Kabat. V_(H) CDRs are herein definedto include residues at positions 27-33 (CDR1), 52-56 (CDR2), and 95-102(CDR3), wherein the numbering is according to Chothia. These V_(H) CDRpositions correspond to Kabat positions 27-35 (CDR1), 52-56 (CDR2), and95-102 (CDR3).

As will be appreciated by those in the art, the CDRs disclosed hereinmay also include variants, for example, when backmutating the CDRsdisclosed herein into different framework regions. Generally, thenucleic acid identity between individual variant CDRs are at least 80%to the sequences depicted herein, and more typically with preferablyincreasing identities of at least 85%, 90%, 91%, 92%, 93%, 94%, 95%,96%, 97%, 98%, 99% and almost 100%. In a similar manner, “percent (%)nucleic acid sequence identity” with respect to the nucleic acidsequence of the binding proteins identified herein is defined as thepercentage of nucleotide residues in a candidate sequence that areidentical with the nucleotide residues in the coding sequence of theantigen binding protein. A specific method utilizes the BLASTN module ofWU-BLAST-2 set to the default parameters, with overlap span and overlapfraction set to 1 and 0.125, respectively and no filters selected.

Generally, the nucleic acid sequence identity between the nucleotidesequences encoding individual variant CDRs and the nucleotide sequencesdepicted herein are at least 80%, and more typically with preferablyincreasing identities of at least 80%, 81%, 82%, 83%, 84%, 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% andalmost 100%.

Thus, a “variant CDR” is one with the specified homology, similarity, oridentity to the parent CDR of the invention, and shares biologicalfunction, including, but not limited to, at least 80%, 81%, 82%, 83%,84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%,98%, or 99% of the specificity and/or activity of the parent CDR.

While the site or region for introducing an amino acid sequencevariation is predetermined, the mutation per se need not bepredetermined. For example, in order to optimize the performance of amutation at a given site, random mutagenesis may be conducted at thetarget codon or region and the expressed antigen binding protein CDRvariants screened for the optimal combination of desired activity.Techniques for making substitution mutations at predetermined sites inDNA having a known sequence are well known, for example, M13 primermutagenesis and PCR mutagenesis. Screening of the mutants is done usingassays of antigen binding protein activities as described herein.

Amino acid substitutions are typically of single residues; insertionsusually will be on the order of from about one (1) to about twenty (20)amino acid residues, although considerably larger insertions may betolerated. Deletions range from about one (1) to about twenty (20) aminoacid residues, although in some cases deletions may be much larger.

Substitutions, deletions, insertions or any combination thereof may beused to arrive at a final derivative or variant. Generally these changesare done on a few amino acids to minimize the alteration of themolecule, particularly the immunogenicity and specificity of the antigenbinding protein. However, larger changes may be tolerated in certaincircumstances.

By “Fab” or “Fab region” as used herein is meant the polypeptide thatcomprises the V_(H), C_(H)1, V_(L), and C_(L) immunoglobulin domains.Fab may refer to this region in isolation, or this region in the contextof a full length antibody, antibody fragment or Fab fusion protein, orany other antibody embodiments as outlined herein.

By “Fv” or “Fv fragment” or “Fv region” as used herein is meant apolypeptide that comprises the V_(L) and V_(H) domains of a singleantibody.

By “framework” as used herein is meant the region of an antibodyvariable domain exclusive of those regions defined as CDRs. Eachantibody variable domain framework can be further subdivided into thecontiguous regions separated by the CDRs (FR1, FR2, FR3 and FR4).

The term “antigen-binding portion” of an antibody (or simply “antibodyportion”), as used herein, refers to one or more fragments of anantibody that retain the ability to specifically bind to an antigen(e.g. BST1). It has been shown that the antigen-binding function of anantibody can be performed by fragments of a full-length antibody.Examples of binding fragments encompassed within the term“antigen-binding portion” of an antibody include (i) a Fab fragment, amonovalent fragment consisting of the V_(L)/V_(K), V_(H), C_(L) andC_(H)1 domains; (ii) a F(ab′)₂ fragment, a bivalent fragment comprisingtwo Fab fragments linked by a disulfide bridge at the hinge region;(iii) a Fab′ fragment, which is essentially an Fab with part of thehinge region (see, FUNDAMENTAL IMMUNOLOGY (Paul ed., 3.sup.rd ed. 1993);(iv) a Fd fragment consisting of the V_(H) and C_(H)1 domains; (v) a Fvfragment consisting of the V_(L) and V_(H) domains of a single arm of anantibody; (vi) a dAb fragment [Ward et al. (1989) Nature 341:544-546],which consists of a V_(H) domain; (vii) an isolated complementaritydetermining region (CDR); and (viii) a Nanobody®, a heavy chain variableregion containing a single variable domain and two constant domains.Furthermore, although the two domains of the Fv fragment, V_(L)/V_(K)and V_(H), are coded for by separate genes, they can be joined, usingrecombinant methods, by a synthetic linker that enables them to be madeas a single protein chain in which the V_(L)/V_(K) and V_(H) regionspair to form monovalent molecules (known as single chain Fv (scFv); seee.g. Bird et al. (1988) Science 242:423-426; and Huston et al. (1988)Proc. Natl. Acad. Sci. USA 85:5879-5883. Such single chain antibodiesare also intended to be encompassed within the term “antigen-bindingportion” of an antibody. These antibody fragments are obtained usingconventional techniques known to those with skill in the art, and thefragments are screened for utility in the same manner as are intactantibodies.

An “isolated antibody” as used herein, is intended to refer to anantibody that is substantially free of other antibodies having differentantigenic specificities (e.g. an isolated antibody that specificallybinds to the BST1 is substantially free of antibodies that specificallybind antigens other than the BST1). An isolated antibody thatspecifically binds to the BST1 may, however, have cross-reactivity toother antigens, such as BST1 molecules from other species. Moreover,and/or alternatively an isolated antibody may be substantially free ofother cellular material and/or chemicals, that is in a form not normallyfound in nature.

In some embodiments, the antibodies of the invention are recombinantproteins, isolated proteins or substantially pure proteins. An“isolated” protein is unaccompanied by at least some of the materialwith which it is normally associated in its natural state, for exampleconstituting at least about 5%, or at least about 50% by weight of thetotal protein in a given sample. It is understood that the isolatedprotein may constitute from 5 to 99.9% by weight of the total proteincontent depending on the circumstances. For example, the protein may bemade at a significantly higher concentration through the use of aninducible promoter or high expression promoter, such that the protein ismade at increased concentration levels. In the case of recombinantproteins, the definition includes the production of an antibody in awide variety of organisms and/or host cells that are known in the art inwhich it is not naturally produced.

The terms “monoclonal antibody” or “monoclonal antibody composition” asused herein refer to a preparation of antibody molecules of singlemolecular composition. A monoclonal antibody composition displays asingle binding specificity and affinity for a particular epitope. Asused herein, a “polyclonal antibody” refers to antibodies produced byseveral clones of B-lymphocytes as would be the case in a whole animal.

As used herein, “isotype” refers to the antibody class (e.g. IgM orIgG1) that is encoded by the heavy chain constant region genes.

The phrases “an antibody recognizing an antigen” and “an antibodyspecific for an antigen” are used interchangeably herein with the term“an antibody which binds specifically to an antigen”.

The term “antibody derivatives” refers to any modified form of theantibody, e.g. a conjugate (generally a chemical linkage) of theantibody and another agent or antibody. For example, antibodies of thepresent invention may be conjugated to agents, including, but notlimited to, polymers (e.g. PEG) toxins, labels, etc. as is more fullydescribed below. The antibodies of the present invention may benonhuman, chimeric, humanized, or fully human. For a description of theconcepts of chimeric and humanized antibodies, see Clark et al. (2000)and references cited therein (Clark, 2000, Immunol Today 21:397-402).Chimeric antibodies comprise the variable region of a nonhuman antibody,for example V_(H) and V_(L) domains of mouse or rat origin, operablylinked to the constant region of a human antibody (see for example U.S.Pat. No. 4,816,567). In a preferred embodiment, the antibodies of thepresent invention are humanized. By “humanized” antibody as used hereinis meant an antibody comprising a human framework region (FR) and one ormore complementarity determining regions (CDR's) from a non-human(usually mouse or rat) antibody. The non-human antibody providing theCDR's is called the “donor” and the human immunoglobulin providing theframework is called the “acceptor”. Humanization relies principally onthe grafting of donor CDRs onto acceptor (human) V_(L) and V_(H)frameworks (U.S. Pat. No. 5,225,539). This strategy is referred to as“CDR grafting”. “Backmutation” of selected acceptor framework residuesto the corresponding donor residues is often required to regain affinitythat is lost in the initial grafted construct (U.S. Pat. No. 5,530,101;U.S. Pat. No. 5,585,089; U.S. Pat. No. 5,693,761; U.S. Pat. No.5,693,762; U.S. Pat. No. 6,180,370; U.S. Pat. No. 5,859,205; U.S. Pat.No. 5,821,337; U.S. Pat. No. 6,054,297; U.S. Pat. No. 6,407,213). Thehumanized antibody optimally also will comprise at least a portion of animmunoglobulin constant region, typically that of a humanimmunoglobulin, and thus will typically comprise a human Fc region.Methods for humanizing non-human antibodies are well known in the art,and can be essentially performed following the method of Winter andco-workers [Jones et al. (1986) Nature 321:522-525; Riechmann et al.(1988) Nature 332:323-329; Verhoeyen et al. (1988) Science,239:1534-1536]. Additional examples of humanized murine monoclonalantibodies are also known in the art, for example antibodies bindinghuman protein C(O'Connor et al., 1998, Protein Eng 11:321-8),interleukin 2 receptor [Queen et al. (1989) Proc Natl Acad Sci, USA86:10029-33], and human epidermal growth factor receptor 2 [Carter etal. (1992) Proc Natl Acad Sci USA 89:4285-9]. In an alternateembodiment, the antibodies of the present invention may be fully human,that is the sequences of the antibodies are completely or substantiallyhuman. A number of methods are known in the art for generating fullyhuman antibodies, including the use of transgenic mice [Bruggemann etal. (1997) Curr Opin Biotechnol 8:455-458] or human antibody librariescoupled with selection methods [Griffiths et al. (1998) Curr OpinBiotechnol 9:102-108].

The term “humanized antibody” is intended to include antibodies in whichCDR sequences derived from the germline of another mammalian species,such as a mouse, have been grafted onto human framework sequences.Additional framework region modifications may be made within the humanframework sequences, such as Fc domain amino acid modifications, as isdescribed herein.

The term “chimeric antibody” is intended to refer to antibodies in whichthe variable region sequences are derived from one species and theconstant region sequences are derived from another species, such as anantibody in which the variable region sequences are derived from a mouseantibody and the constant region sequences are derived from a humanantibody.

The term “specifically binds” (or “immunospecifically binds”) is notintended to indicate that an antibody binds exclusively to its intendedtarget, although in many embodiments this will be true; that is, anantibody “specifically binds” to its target and does not detectably orsubstantially bind to other components in the sample, cell or patient.However, in some embodiments, an antibody “specifically binds” if itsaffinity for its intended target is about 5-fold greater when comparedto its affinity for a non-target molecule. Suitably there is nosignificant cross-reaction or cross-binding with undesired substances,especially naturally occurring proteins or tissues of a healthy personor animal. The affinity of the antibody will, for example, be at leastabout 5-fold, such as 10-fold, such as 25-fold, especially 50-fold, andparticularly 100-fold or more, greater for a target molecule than itsaffinity for a non-target molecule. In some embodiments, specificbinding between an antibody or other binding agent and an antigen meansa binding affinity of at least 10⁶ M⁻¹. Antibodies may, for example,bind with affinities of at least about 10⁷ M⁻¹, such as between about10⁸ M⁻¹ to about 10⁹ M⁻¹, about 10⁹ M⁻¹ to about 10¹⁰ M⁻¹, or about 10¹⁰M⁻¹ to about 10¹¹ M⁻¹. Antibodies may, for example, bind with an EC₅₀ of50 nM or less, 10 nM or less, 1 nM or less, 100 pM or less, or morepreferably 10 pM or less.

The term “does not substantially bind” to a protein or cells, as usedherein, means does not bind or does not bind with a high affinity to theprotein or cells, i.e. binds to the protein or cells with a K_(D) of1×10⁻⁶ M or more, more preferably 1×10⁻⁵ M or more, more preferably1×10⁻⁴ M or more, more preferably 1×10⁻³ M or more, even more preferably1×10⁻² M or more.

The term “EC₅₀” as used herein, is intended to refer to the potency of acompound by quantifying the concentration that leads to 50% maximalresponse/effect. EC₅₀ may be determined by Scratchard or FACS.

The term “K_(assoc)” or “K_(a),” as used herein, is intended to refer tothe association rate of a particular antibody-antigen interaction,whereas the term “K_(dis)” or “K_(d),” as used herein, is intended torefer to the dissociation rate of a particular antibody-antigeninteraction. The term “K_(D),” as used herein, is intended to refer tothe affinity constant, which is obtained from the ratio of K_(d) toK_(a) (i.e. K_(d)/K_(a)) and is expressed as a molar concentration (M).K_(D) values for antibodies can be determined using methods wellestablished in the art. A preferred method for determining the K_(D) ofan antibody is by using surface plasmon resonance, preferably using abiosensor system such as a Biacore® system.

As used herein, the term “high affinity” for an IgG antibody refers toan antibody having a K_(D) of 1×10⁻⁷ M or less, more preferably 5×10⁻⁸ Mor less, even more preferably 1×10⁻⁸ M or less, even more preferably5×10⁻⁹ M or less and even more preferably 1×10⁻⁹ M or less for a targetantigen. However, “high affinity” binding can vary for other antibodyisotypes. For example, “high affinity” binding for an IgM isotype refersto an antibody having a K_(D) of 10⁻⁶ M or less, more preferably 10⁻⁷ Mor less, even more preferably 10⁻⁸ M or less.

The term “epitope” or “antigenic determinant” refers to a site on anantigen to which an immunoglobulin or antibody specifically binds.Epitopes can be formed both from contiguous amino acids or noncontiguousamino acids juxtaposed by tertiary folding of a protein. Epitopes formedfrom contiguous amino acids are typically retained on exposure todenaturing solvents, whereas epitopes formed by tertiary folding aretypically lost on treatment with denaturing solvents. An epitopetypically includes at least 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or15 amino acids in a unique spatial conformation. Methods of determiningspatial conformation of epitopes include techniques in the art and thosedescribed herein, for example, x-ray crystallography and 2-dimensionalnuclear magnetic resonance [see, e.g. Epitope Mapping Protocols inMethods in Molecular Biology, Vol. 66, G. E. Morris, Ed. (1996)].

Accordingly, also encompassed by the present invention are antibodiesthat bind to (i.e. recognize) the same epitope as the antibodiesdescribed herein (i.e. BST1_A2, BST1_A1 and BST1_A3). Antibodies thatbind to the same epitope can be identified by their ability tocross-compete with (i.e. competitively inhibit binding of) a referenceantibody to a target antigen in a statistically significant manner.Competitive inhibition can occur, for example, if the antibodies bind toidentical or structurally similar epitopes (e.g. overlapping epitopes),or spatially proximal epitopes which, when bound, causes sterichindrance between the antibodies.

Competitive inhibition can be determined using routine assays in whichthe immunoglobulin under test inhibits specific binding of a referenceantibody to a common antigen. Numerous types of competitive bindingassays are known, for example: solid phase direct or indirectradioimmunoassay (RIA), solid phase direct or indirect enzymeimmunoassay (EIA), sandwich competition assay [see Stahl et al. (1983)Methods in Enzymology 9:242]; solid phase direct biotin-avidin EIA [seeKirkland et al. (1986) J. Immunol. 137:3614]; solid phase direct labeledassay, solid phase direct labeled sandwich assay [see Harlow and Lane(1988) Antibodies: A Laboratory Manual, Cold Spring Harbor Press]; solidphase direct label RIA using I-125 label [see Morel et al. (1988) Mol.Immunol. 25(1):7)]; solid phase direct biotin-avidin EIA [Cheung et al.(1990) Virology 176:546]; and direct labeled RIA. [Moldenhauer et al.(1990) Scand. J. Immunol. 32:77]. Typically, such an assay involves theuse of purified antigen bound to a solid surface or cells bearing eitherof these, an unlabeled test immunoglobulin and a labeled referenceimmunoglobulin. Competitive inhibition is measured by determining theamount of label bound to the solid surface or cells in the presence ofthe test immunoglobulin. Usually the test immunoglobulin is present inexcess. Usually, when a competing antibody is present in excess, it willinhibit specific binding of a reference antibody to a common antigen byat least 50-55%, 55-60%, 60-65%, 65-70% 70-75% or more.

Other techniques include, for example, epitope mapping methods, such asx-ray analyses of crystals of antigen:antibody complexes which providesatomic resolution of the epitope. Other methods monitor the binding ofthe antibody to antigen fragments or mutated variations of the antigenwhere loss of binding due to a modification of an amino acid residuewithin the antigen sequence is often considered an indication of anepitope component. In addition, computational combinatorial methods forepitope mapping can also be used. These methods rely on the ability ofthe antibody of interest to affinity isolate specific short peptidesfrom combinatorial phage display peptide libraries. The peptides arethen regarded as leads for the definition of the epitope correspondingto the antibody used to screen the peptide library. For epitope mapping,computational algorithms have also been developed which have been shownto map conformational discontinuous epitopes.

As used herein, the term “subject” includes any human or nonhumananimal. The term “nonhuman animal” includes all vertebrates, e.g.mammals and non-mammals, such as nonhuman primates, sheep, dogs, cats,horses, cows, chickens, amphibians, reptiles, etc.

Various aspects of the disclosure are described in further detail in thefollowing subsections.

Anti-BST1 Antibodies

The antibodies of the invention are characterized by particularfunctional features or properties of the antibodies. For example, theantibodies bind specifically to the human BST1. Preferably, an antibodyof the invention binds to the BST1 with high affinity, for example, witha K_(D) of 8×10⁻⁷ M or less, even more typically 1×10⁻⁸ M or less. Theanti-BST1 antibodies of the invention preferably exhibit one or more ofthe following characteristics, with antibodies exhibiting both findingparticular use:

binds to the human BST1 with a EC₅₀ of 50 nM or less, 10 nM or less, 1nM or less, 100 pM or less, or more preferably 10 pM or less;

binds to human cells expressing the BST1.

In one embodiment, the antibodies preferably bind to an antigenicepitope present in the BST1, which epitope is not present in otherproteins. Preferably, the antibodies do not bind to related proteins,for example, the antibodies do not substantially bind to other celladhesion molecules. In one embodiment, the antibody may be internalizedinto a cell expressing the BST1. Standard assays to evaluate antibodyinternalization are known in the art, including, for example, MabZap orHumZap internalization assays.

Standard assays to evaluate the binding ability of the antibodies towardthe BST1 can be done on the protein or cellular level and are known inthe art, including for example, ELISAs, Western blots, RIAs, BIAcore®assays and flow cytometry analysis. Suitable assays are described indetail in the Examples. The binding kinetics (e.g. binding affinity) ofthe antibodies also can be assessed by standard assays known in the art,such as by Biacore® system analysis. To assess binding to Raji or DaudiB cell tumor cells, Raji (ATCC Deposit No. CCL-86) or Daudi (ATCCDeposit No. CCL-213) cells can be obtained from publicly availablesources, such as the American Type Culture Collection, and used instandard assays, such as flow cytometric analysis.

Monoclonal Antibodies of the Invention

Preferred antibodies of the invention are the monoclonal antibodiesBST1_A2 and BST1_A1 isolated and structurally characterized as describedin Examples 1-4. The V_(H) amino acid sequences BST1_A2, BST1_A1 andBST1_A3 are shown in SEQ ID NOs: 2, 1 and 52, respectively. The V_(K)amino acid sequences BST1_A2, BST1_A1 and BST1_A3 are shown in SEQ IDNOs: 4, 3 and 53, respectively.

Given that each of these antibodies can bind to the BST1, the V_(H) andV_(K) sequences can be “mixed and matched” to create other anti-BST1binding molecules of the invention. The BST1 binding of such “mixed andmatched” antibodies can be tested using the binding assays describedabove and in the Examples (e.g. ELISAs). Preferably, when V_(H) andV_(K) chains are mixed and matched, a V_(H) sequence from a particularV_(H)/V_(K) pairing is replaced with a structurally similar V_(H)sequence. Likewise, preferably a V_(K) sequence from a particularV_(H)/V_(K) pairing is replaced with a structurally similar V_(K)sequence.

Accordingly, in one aspect, the invention provides an antibody,comprising:

a heavy chain variable region comprising an amino acid sequence setforth in a SEQ ID NO: selected from the group consisting of 2, 1 and 52and a light chain variable region comprising an amino acid sequence setforth in a SEQ ID NO: selected from the group consisting 4, 3 and 53;wherein the antibody specifically binds to the BST1, preferably thehuman BST1.

Preferred heavy and light chain combinations include:

a heavy chain variable region comprising the amino acid sequence of SEQID NO: 2 and a light chain variable region comprising the amino acidsequence of SEQ ID NO: 4; or

a heavy chain variable region comprising the amino acid sequence of SEQID NO: 1 and a light chain variable region comprising the amino acidsequence of SEQ ID NO: 3; or

a heavy chain variable region comprising the amino acid sequence of SEQID NO: 52 and a light chain variable region comprising the amino acidsequence of SEQ ID NO: 53.

In another aspect, the invention provides antibodies that comprise theheavy chain and light chain CDR1s, CDR2s and CDR3s of BST1_A2, BST1_A1and BST1_A3, or combinations thereof. The amino acid sequences of theV_(H) CDR1s of BST1_A2, BST1_A1 and BST1_A3 are shown in SEQ ID NOs: 10,9 and 56, respectively. The amino acid sequences of the V_(H) CDR2s ofBST1_A2, BST1_A1 and BST1_A3 are shown in SEQ ID NOs: 12 or 51, 11 and57, respectively. The amino acid sequences of the V_(H) CDR3s ofBST1_A2, BST1_A1 and BST1_A3 are shown in SEQ ID NOs: 14, 13 and 58,respectively. The amino acid sequences of the V_(K) CDR1s of BST1_A2,BST1_A1 and BST1_A3 are shown in SEQ ID NOs: 16, 15 and 59,respectively. The amino acid sequences of the V_(K) CDR2s of BST1_A2,BST1_A1 and BST1_A3 are shown in SEQ ID NOs: 18, 17 and 60,respectively. The amino acid sequences of the V_(K) CDR3s of BST1_A2,BST1_A1 and BST1_A3 are shown in SEQ ID NOs: 20, 19 and 61,respectively. The CDR regions are delineated using the Kabat system[Kabat, E. A. et al. (1991) Sequences of Proteins of ImmunologicalInterest, Fifth Edition, US Department of Health and Human Services, NIHPublication No. 91-3242].

Given that each of these antibodies can bind to the BST1 and thatantigen-binding specificity is provided primarily by the CDR1, CDR2, andCDR3 regions, the V_(H) CDR1, CDR2, and CDR3 sequences and V_(K) CDR1,CDR2, and CDR3 sequences can be “mixed and matched” (i.e. CDRs fromdifferent antibodies can be mixed and matched, although each antibodygenerally contains a V_(H) CDR1, CDR2, and CDR3 and a V_(K) CDR1, CDR2,and CDR3) to create other anti-BST1 binding molecules of the invention.Accordingly, the invention specifically includes every possiblecombination of CDRs of the heavy and light chains.

The BST1 binding of such “mixed and matched” antibodies can be testedusing the binding assays described above and in the Examples (e.g.ELISAs, Biacore® analysis). Preferably, when V_(H) CDR sequences aremixed and matched, the CDR1, CDR2 and/or CDR3 sequence from a particularV_(H) sequence is replaced with a structurally similar CDR sequence(s).Likewise, when V_(K) CDR sequences are mixed and matched, the CDR1, CDR2and/or CDR3 sequence from a particular V_(K) sequence preferably isreplaced with a structurally similar CDR sequence(s). It will be readilyapparent to the ordinarily skilled artisan that novel V_(H) and V_(K)sequences can be created by substituting one or more V_(H) and/orV_(L)/V_(K) CDR region sequences with structurally similar sequencesfrom the CDR sequences disclosed herein for monoclonal antibodiesBST1_A2, BST1_A1 and BST1_A3.

Accordingly, in another aspect, the invention provides an isolatedmonoclonal antibody, or antigen binding portion thereof comprising:

-   -   a heavy chain variable region CDR1 comprising an amino acid        sequence selected from the group consisting of SEQ ID NOs: 10, 9        and 56;    -   a heavy chain variable region CDR2 comprising an amino acid        sequence selected from the group consisting of SEQ ID NOs: 12 or        51, 11 and 57;    -   a heavy chain variable region CDR3 comprising an amino acid        sequence selected from the group consisting of SEQ ID NOs: 14,        13 and 58;    -   a light chain variable region CDR1 comprising an amino acid        sequence selected from the group consisting of SEQ ID NOs: 16,        15 and 59;    -   a light chain variable region CDR2 comprising an amino acid        sequence selected from the group consisting of SEQ ID NOs: 18,        17 and 60; and    -   a light chain variable region CDR3 comprising an amino acid        sequence selected from the group consisting of SEQ ID NOs: 20,        19 and 61;    -   with all possible combinations being possible, wherein the        antibody specifically binds to the BST1, preferably the human        BST1.

In another preferred embodiment, the antibody possesses:

-   -   a heavy chain variable region CDR1 comprising SEQ ID NO: 10;    -   a heavy chain variable region CDR2 comprising SEQ ID NO: 12 or        SEQ ID NO: 51;    -   a heavy chain variable region CDR3 comprising SEQ ID NO: 14; and    -   a light chain variable region CDR1 comprising SEQ ID NO: 16;    -   a light chain variable region CDR2 comprising SEQ ID NO: 18;    -   a light chain variable region CDR3 comprising SEQ ID NO: 20.

In another preferred embodiment, the antibody possesses:

-   -   a heavy chain variable region CDR1 comprising SEQ ID NO: 9;    -   a heavy chain variable region CDR2 comprising SEQ ID NO: 11;    -   a heavy chain variable region CDR3 comprising SEQ ID NO: 13; and    -   a light chain variable region CDR1 comprising SEQ ID NO: 15;    -   a light chain variable region CDR2 comprising SEQ ID NO: 17;    -   a light chain variable region CDR3 comprising SEQ ID NO: 19.

In another preferred embodiment, the antibody possesses:

-   -   a heavy chain variable region CDR1 comprising SEQ ID NO: 56;    -   a heavy chain variable region CDR2 comprising SEQ ID NO: 57;    -   a heavy chain variable region CDR3 comprising SEQ ID NO: 58; and    -   a light chain variable region CDR1 comprising SEQ ID NO: 59;    -   a light chain variable region CDR2 comprising SEQ ID NO: 60;    -   a light chain variable region CDR3 comprising SEQ ID NO: 61.

It is well known in the art that the CDR3 domain, independently from theCDR1 and/or CDR2 domain(s), alone can determine the binding specificityof an antibody for a cognate antigen and that multiple antibodies canpredictably be generated having the same binding specificity based on acommon CDR3 sequence. See, for example, Klimka et al. (2000) British J.of Cancer 83(2):252-260 (describing the production of a humanizedanti-CD30 antibody using only the heavy chain variable domain CDR3 ofmurine anti-CD30 antibody Ki-4); Beiboer et al. (2000) J. Mol. Biol.296:833-849 (describing recombinant epithelial glycoprotein-2 (EGP-2)antibodies using only the heavy chain CDR3 sequence of the parentalmurine MOC-31 anti-EGP-2 antibody); Rader et al. (1998) Proc. Natl.Acad. Sci. USA. 95:8910-8915 (describing a panel of humanizedanti-integrin α_(v)β₃ antibodies using a heavy and light chain variableCDR3 domain of a murine anti-integrin α_(v)β₃ antibody LM609 whereineach member antibody comprises a distinct sequence outside the CDR3domain and capable of binding the same epitope as the parent murineantibody with affinities as high or higher than the parent murineantibody); Barbas et al. (1994) J. Am. Chem. Soc. 116:2161-2162(disclosing that the CDR3 domain provides the most significantcontribution to antigen binding); Barbas et al. (1995) Proc. Natl. Acad.Sci. USA. 92:2529-2533 (describing the grafting of heavy chain CDR3sequences of three Fabs (SI-1, SI-40, and SI-32) against human placentalDNA onto the heavy chain of an anti-tetanus toxoid Fab thereby replacingthe existing heavy chain CDR3 and demonstrating that the CDR3 domainalone conferred binding specificity); and Ditzel et al. (1996) J.Immunol. 157:739-749 (describing grafting studies wherein transfer ofonly the heavy chain CDR3 of a parent polyspecific Fab LNA3 to a heavychain of a monospecific IgG tetanus toxoid-binding Fab p313 antibody wassufficient to retain binding specificity of the parent Fab). Each ofthese references is hereby incorporated by reference in its entirety.

Accordingly, the present invention provides monoclonal antibodiescomprising one or more heavy and/or light chain CDR3 domains from anantibody derived from a human or non-human animal, wherein themonoclonal antibody is capable of specifically binding to the BST1.Within certain aspects, the present invention provides monoclonalantibodies comprising one or more heavy and/or light chain CDR3 domainfrom a non-human antibody, such as a mouse or rat antibody, wherein themonoclonal antibody is capable of specifically binding to the BST1.Within some embodiments, such inventive antibodies comprising one ormore heavy and/or light chain CDR3 domain from a non-human antibody (a)are capable of competing for binding with; (b) retain the functionalcharacteristics; (c) bind to the same epitope; and/or (d) have a similarbinding affinity as the corresponding parental non-human antibody.

Within other aspects, the present invention provides monoclonalantibodies comprising one or more heavy and/or light chain CDR3 domainsfrom a human antibody, such as, for example, a human antibody obtainedfrom a non-human animal, wherein the human antibody is capable ofspecifically binding to the BST1. Within other aspects, the presentinvention provides monoclonal antibodies comprising one or more heavyand/or light chain CDR3 domain from a first human antibody, such as, forexample, a human antibody obtained from a non-human animal, wherein thefirst human antibody is capable of specifically binding to the BST1 andwherein the CDR3 domain from the first human antibody replaces a CDR3domain in a human antibody that is lacking binding specificity for theBST1 to generate a second human antibody that is capable of specificallybinding to the BST1. Within some embodiments, such inventive antibodiescomprising one or more heavy and/or light chain CDR3 domain from thefirst human antibody (a) are capable of competing for binding with; (b)retain the functional characteristics; (c) bind to the same epitope;and/or (d) have a similar binding affinity as the corresponding parentalfirst human antibody.

Antibodies Having Particular Germline Sequences

In certain embodiments, an antibody of the invention comprises a heavychain variable region from a particular germline heavy chainimmunoglobulin gene and/or a light chain variable region from aparticular germline light chain immunoglobulin gene.

For example, in a preferred embodiment, the invention provides anisolated monoclonal antibody, or an antigen-binding portion thereof,comprising a heavy chain variable region that is the product of orderived from a murine V_(H) 1-39 gene, murine V_(H) 1-80 gene or amurine V_(H) 69-1 gene, wherein the antibody specifically binds to theBST1. In yet another preferred embodiment, the invention provides anisolated monoclonal antibody, or an antigen-binding portion thereof,comprising a light chain variable region that is the product of orderived from a murine V_(K) 4-55 gene, murine V_(K) 4-74 gene or amurine V_(K) 44-1 gene, wherein the antibody specifically binds to theBST1.

In yet another preferred embodiment, the invention provides an isolatedmonoclonal antibody, or antigen-binding portion thereof, wherein theantibody:

comprises a heavy chain variable region that is the product of orderived from a murine V_(H) 1-39 gene (which gene includes thenucleotide sequence set forth in SEQ ID NOs: 35 and 36); comprises alight chain variable region that is the product of or derived from amurine V_(K) 4-55 gene (which gene includes the nucleotide sequences setforth in SEQ ID NOs: 40, 41 and 42); and specifically binds to the BST1,preferably the human BST1. Examples of antibodies having V_(H) 1-39 andV_(K) 4-55 genes, with sequences described above, are BST1_A2.

In yet another preferred embodiment, the invention provides an isolatedmonoclonal antibody, or antigen-binding portion thereof, wherein theantibody:

comprises a heavy chain variable region that is the product of orderived from a murine V_(H) 1-80 gene (which gene includes thenucleotide sequence set forth in SEQ ID NOs: 33 and 34);

comprises a light chain variable region that is the product of orderived from a murine V_(K) 4-74 gene (which gene includes thenucleotide sequences set forth in SEQ ID NOs: 37, 38 and 39); andspecifically binds to the BST1, preferably the human BST1. An example ofan antibody having V_(H) 1-80 and V_(K) 4-74 genes, with sequencesdescribed above, is BST1_A1.

In yet another preferred embodiment, the invention provides an isolatedmonoclonal antibody, or antigen-binding portion thereof, wherein theantibody:

comprises a heavy chain variable region that is the product of orderived from a murine V_(H) 69-1 gene (which gene includes thenucleotide sequence set forth in SEQ ID NOs: 68 and 69);

comprises a light chain variable region that is the product of orderived from a murine V_(K) 44-1 gene (which gene includes thenucleotide sequences set forth in SEQ ID NOs: 70, 71 and 72); andspecifically binds to the BST1, preferably the human BST1. An example ofan antibody having V_(H) and V_(K) genes, with sequences describedabove, is BST1_A3.

As used herein, an antibody comprises heavy or light chain variableregions that is “the product of” or “derived from” a particular germlinesequence if the variable regions of the antibody are obtained from asystem that uses murine germline immunoglobulin genes. Such systemsinclude screening a murine immunoglobulin gene library displayed onphage with the antigen of interest. An antibody that is “the product of”or “derived from” a murine germline immunoglobulin sequence can beidentified as such by comparing the nucleotide or amino acid sequence ofthe antibody to the nucleotide or amino acid sequences of murinegermline immunoglobulins and selecting the murine germlineimmunoglobulin sequence that is closest in sequence (i.e. greatest %identity) to the sequence of the antibody. An antibody that is “theproduct of” or “derived from” a particular murine germlineimmunoglobulin sequence may contain amino acid differences as comparedto the germline sequence, due to, for example, naturally-occurringsomatic mutations or intentional introduction of site-directed mutation.However, a selected antibody typically is at least 90% identical inamino acids sequence to an amino acid sequence encoded by a murinegermline immunoglobulin gene and contains amino acid residues thatidentify the antibody as being murine when compared to the germlineimmunoglobulin amino acid sequences of other species (e.g. humangermline sequences). In certain cases, an antibody may be at least 95%,or even at least 96%, 97%, 98%, or 99% identical in amino acid sequenceto the amino acid sequence encoded by the germline immunoglobulin gene.Typically, an antibody derived from a particular murine germlinesequence will display no more than 10 amino acid differences from theamino acid sequence encoded by the murine germline immunoglobulin gene.In certain cases, the antibody may display no more than 5, or even nomore than 4, 3, 2, or 1 amino acid difference from the amino acidsequence encoded by the germline immunoglobulin gene.

Homologous Antibodies

In yet another embodiment, an antibody of the invention comprises heavyand light chain variable regions comprising amino acid sequences thatare homologous to the amino acid sequences of the preferred antibodiesdescribed herein, and wherein the antibodies retain the desiredfunctional properties of the anti-BST1 antibodies of the invention.

For example, the invention provides an isolated monoclonal antibody, orantigen binding portion thereof, comprising a heavy chain variableregion and a light chain variable region, wherein: the heavy chainvariable region comprises an amino acid sequence that is at least 80%identical to an amino acid sequence selected from the group consistingof SEQ ID NOs: 2, 1 and 52; the light chain variable region comprises anamino acid sequence that is at least 80% identical to an amino acidsequence selected from the group consisting of SEQ ID NOs: 4, 3 and 53;and the antibody binds to human BST1. Such antibodies may bind to humanBST1 with an EC₅₀ of 50 nM or less, 10 nM or less, 1 nM or less, 100 pMor less, or more preferably 10 pM or less.

The antibody may also bind to CHO cells transfected with the human BST1.

In various embodiments, the antibody can be, for example, a humanantibody, a humanized antibody or a chimeric antibody.

In other embodiments, the V_(H) and/or V_(K) amino acid sequences may be85%, 90%, 95%, 96%, 97%, 98% or 99% homologous to the sequences setforth above. An antibody having V_(H) and V_(K) regions having high(i.e. 80% or greater) identical to the V_(H) and V_(K) regions of thesequences set forth above, can be obtained by mutagenesis (e.g.site-directed or PCR-mediated mutagenesis) of nucleic acid moleculesencoding SEQ ID NOs: 6, 5, 8, 7, 54 and 55 followed by testing of theencoded altered antibody for retained function using the functionalassays described herein.

The percent identity between the two sequences is a function of thenumber of identical positions shared by the sequences (i.e. % homology=#of identical positions/total # of positions×100), taking into accountthe number of gaps, and the length of each gap, which need to beintroduced for optimal alignment of the two sequences. The comparison ofsequences and determination of percent identity between two sequencescan be accomplished using a mathematical algorithm, as described in thenon-limiting examples below.

The percent identity between two amino acid sequences can be determinedusing the algorithm of E. Meyers and W. Miller [Comput. Appl. Biosci.(1988) 4:11-17] which has been incorporated into the ALIGN program(version 2.0), using a PAM120 weight residue table, a gap length penaltyof 12 and a gap penalty of 4. In addition, the percent identity betweentwo amino acid sequences can be determined using the Needleman andWunsch [J. Mol. Biol. (1970) 48:444-453] algorithm which has beenincorporated into the GAP program in the GCG software package (availableat http://www.gcg.com), using either a Blossum 62 matrix or a PAM250matrix, and a gap weight of 16, 14, 12, 10, 8, 6, or 4 and a lengthweight of 1, 2, 3, 4, 5, or 6.

Additionally or alternatively, the protein sequences of the presentinvention can further be used as a “query sequence” to perform a searchagainst public databases to, for example, identify related sequences.Such searches can be performed using the XBLAST program (version 2.0) ofAltschul, et al. (1990) J. Mol. Biol. 215:403-10. BLAST protein searchescan be performed with the XBLAST program, score=50, wordlength=3 toobtain amino acid sequences homologous to the antibody molecules of theinvention. To obtain gapped alignments for comparison purposes, GappedBLAST can be utilized as described in Altschul et al., (1997) NucleicAcids Res. 25(17):3389-3402. When utilizing BLAST and Gapped BLASTprograms, the default parameters of the respective programs (e.g. XBLASTand NBLAST) can be used. See www.ncbi.nlm.nih.gov.

Antibodies with Conservative Modifications

In certain embodiments, an antibody of the invention comprises a heavychain variable region comprising CDR1, CDR2 and CDR3 sequences and alight chain variable region comprising CDR1, CDR2 and CDR3 sequences,wherein one or more of these CDR sequences comprise specified amino acidsequences based on the preferred antibodies described herein (e.g.BST1_A2, BST1_A1 and BST1_A3), or conservative modifications thereof,and wherein the antibodies retain the desired functional properties ofthe anti-BST1 antibodies of the invention. Accordingly, the inventionprovides an isolated monoclonal antibody, or antigen binding portionthereof, comprising a heavy chain variable region comprising CDR1, CDR2,and CDR3 sequences and a light chain variable region comprising CDR1,CDR2, and CDR3 sequences, wherein: the heavy chain variable region CDR3sequence comprises an amino acid sequence selected from the groupconsisting of amino acid sequences of SEQ ID NOs: 14, 13 and 58, andconservative modifications thereof; the light chain variable region CDR3sequence comprises an amino acid sequence selected from the groupconsisting of amino acid sequence of SEQ ID NOs: 20, 19 and 61, andconservative modifications thereof; and the antibody binds to human BST1with a EC₅₀ of 50 nM or less, 10 nM or less, 1 nM or less, 100 pM orless, or more preferably 10 pM or less.

The antibody may also bind to CHO cells transfected with human BST1.

In a preferred embodiment, the heavy chain variable region CDR2 sequencecomprises an amino acid sequence selected from the group consisting ofamino acid sequences of SEQ ID NOs: 12 or 51, 11 and 57, andconservative modifications thereof; and the light chain variable regionCDR2 sequence comprises an amino acid sequence selected from the groupconsisting of amino acid sequences of SEQ ID NOs: 18, 17 and 60, andconservative modifications thereof. In another preferred embodiment, theheavy chain variable region CDR1 sequence comprises an amino acidsequence selected from the group consisting of amino acid sequences ofSEQ ID NOs: 10, 9 and 56, and conservative modifications thereof; andthe light chain variable region CDR1 sequence comprises an amino acidsequence selected from the group consisting of amino acid sequences ofSEQ ID NOs: 16, 15 and 59, and conservative modifications thereof. Inanother preferred embodiment, the heavy chain variable region CDR3sequence comprises an amino acid sequence selected from the groupconsisting of amino acid sequences of SEQ ID NOs: 14, 13 and 58, andconservative modifications thereof; and the light chain variable regionCDR3 sequence comprises an amino acid sequence selected from the groupconsisting of amino acid sequences of SEQ ID NOs: 20, 19 and 61, andconservative modifications thereof.

In a preferred embodiment, the heavy chain variable region CDR2 sequencecomprises an amino acid sequence selected from the group consisting ofamino acid sequences of SEQ ID NOs: 12 or 51, 11 and 57, andconservative modifications thereof; and the light chain variable regionCDR2 sequence comprises an amino acid sequence selected from the groupconsisting of amino acid sequences of SEQ ID NOs: 18, 17 and 60, andconservative modifications thereof. In another preferred embodiment, theheavy chain variable region CDR1 sequence comprises an amino acidsequence selected from the group consisting of amino acid sequences ofSEQ ID NOs: 10, 9 and 56, and conservative modifications thereof; andthe light chain variable region CDR1 sequence comprises an amino acidsequence selected from the group consisting of amino acid sequences ofSEQ ID NOs: 16, 15 and 59, and conservative modifications thereof.

In various embodiments, the antibody can be, for example, humanantibodies, humanized antibodies or chimeric antibodies.

As used herein, the term “conservative sequence modifications” isintended to refer to amino acid modifications that do not significantlyaffect or alter the binding characteristics of the antibody containingthe amino acid sequence. Such conservative modifications include aminoacid substitutions, additions and deletions. Modifications can beintroduced into an antibody of the invention by standard techniquesknown in the art, such as site-directed mutagenesis and PCR-mediatedmutagenesis. Conservative amino acid substitutions are ones in which theamino acid residue is replaced with an amino acid residue having asimilar side chain. Families of amino acid residues having similar sidechains have been defined in the art. These families include amino acidswith basic side chains (e.g. lysine, arginine, histidine), acidic sidechains (e.g. aspartic acid, glutamic acid), uncharged polar side chains(e.g. glycine, asparagine, glutamine, serine, threonine, tyrosine,cysteine, tryptophan), nonpolar side chains (e.g. alanine, valine,leucine, isoleucine, proline, phenylalanine, methionine), beta-branchedside chains (e.g. threonine, valine, isoleucine) and aromatic sidechains (e.g. tyrosine, phenylalanine, tryptophan, histidine). Thus, oneor more amino acid residues within the CDR regions of an antibody of theinvention can be replaced with other amino acid residues from the sameside chain family and the altered antibody can be tested for retainedfunction using the functional assays described herein.

The heavy chain CDR1 sequences of SEQ ID NOs: 10, 9 and 56 may compriseone or more conservative sequence modification, such as one, two, three,four, five or more amino acid substitutions, additions or deletions; thelight chain CDR1 sequences of SEQ ID NOs: 16, 15 and 59 may comprise oneor more conservative sequence modification, such as one, two, three,four, five or more amino acid substitutions, additions or deletions; theheavy chain CDR2 sequences shown in SEQ ID NO: 12 or 51, 11 and 57 maycomprise one or more conservative sequence modification, such as one,two, three, four, five or more amino acid substitutions, additions ordeletions; the light chain CDR2 sequences shown in SEQ ID NOs: 18, 17and 60 may comprise one or more conservative sequence modification, suchas one, two, three, four, five or more amino acid substitutions,additions or deletions; the heavy chain CDR3 sequences shown in SEQ IDNOs: 14, 13 and 58 may comprise one or more conservative sequencemodification, such as one, two, three, four, five or more amino acidsubstitutions, additions or deletions; and/or the light chain CDR3sequences shown in SEQ ID NOs: 20, 19 and 61 may comprise one or moreconservative sequence modification, such as one, two, three, four, fiveor more amino acid substitutions, additions or deletions.

Antibodies that Bind to the Same Epitope as Anti-BST1 Antibodies of theInvention

In another embodiment, the invention provides antibodies that bind tothe same epitope on the human BST1 as any of the BST1 monoclonalantibodies of the invention (i.e. antibodies that have the ability tocross-compete for binding to the BST1 with any of the monoclonalantibodies of the invention). In preferred embodiments, the referenceantibody for cross-competition studies can be the monoclonal antibodyBST1_A2 (having V_(H) and V_(K) sequences as shown in SEQ ID NOs: 2 and4, respectively), the monoclonal antibody BST1_A1 (having V_(H) andV_(K) sequences as shown in SEQ ID NOs: 1 and 3, respectively), themonoclonal antibody BST1_A3 (having V_(H) and V_(K) sequences as shownin SEQ ID NOs: 52 and 53, respectively).

Such cross-competing antibodies can be identified based on their abilityto cross-compete with BST1_A2, BST1_A1 and BST1_A3 in standard BST1binding assays. For example, BIAcore analysis, ELISA assays or flowcytometry may be used to demonstrate cross-competition with theantibodies of the current invention. The ability of a test antibody toinhibit the binding of, for example, BST1_A2, BST1_A1 and BST1_A3, tohuman BST1 demonstrates that the test antibody can compete with BST1_A2,BST1_A1 or BST1_A3 for binding to human BST1 and thus binds to the sameepitope on human BST1_A2, BST1_A1 or BST1_A3.

Engineered and Modified Antibodies

An antibody of the invention can be prepared using an antibody havingone or more of the V_(H) and/or V_(L) sequences disclosed herein whichcan be used as starting material to engineer a modified antibody, whichmodified antibody may have altered properties as compared to thestarting antibody. An antibody can be engineered by modifying one ormore amino acids within one or both variable regions (i.e. V_(H) and/orV_(L)), for example, within one or more CDR regions and/or within one ormore framework regions. Additionally or alternatively, an antibody canbe engineered by modifying residues within the constant region(s), forexample to alter the effector function(s) of the antibody.

In certain embodiments, CDR grafting can be used to engineer variableregions of antibodies. Antibodies interact with target antigenspredominantly through amino acid residues that are located in the sixheavy and light chain complementarity determining regions (CDRs). Forthis reason, the amino acid sequences within CDRs are more diversebetween individual antibodies than sequences outside of CDRs. BecauseCDR sequences are responsible for most antibody-antigen interactions, itis possible to express recombinant antibodies that mimic the propertiesof specific naturally occurring antibodies by constructing expressionvectors that include CDR sequences from the specific naturally occurringantibody grafted onto framework sequences from a different antibody withdifferent properties (see, e.g. Riechmann, L. et al. (1998) Nature332:323-327; Jones, P. et al. (1986) Nature 321:522-525; Queen, C. etal. (1989) Proc. Natl. Acad. See. USA. 86:10029-10033; U.S. Pat. No.5,225,539 to Winter, and U.S. Pat. Nos. 5,530,101; 5,585,089; 5,693,762and 6,180,370 to Queen et al.).

Accordingly, another embodiment of the invention pertains to an isolatedmonoclonal antibody, or antigen binding portion thereof, comprising aheavy chain variable region comprising CDR1, CDR2, and CDR3 sequencescomprising an amino acid sequence selected from the group consisting ofSEQ ID NOs 10, 9 and 56; 12 or 51, 11 and 57; and 14, 13 and 58,respectively, and a light chain variable region comprising CDR1, CDR2,and CDR3 sequences comprising an amino acid sequence selected from thegroup consisting of SEQ ID NOs: 16, 15 and 59; 18, 17 and 60; and 20, 19and 61, respectively. Thus, such antibodies contain the V_(H) and V_(K)CDR sequences of monoclonal antibodies BST1_A2, BST1_A1 and BST1_A3, yetmay contain different framework sequences from these antibodies.

Such framework sequences can be obtained from public DNA databases orpublished references that include germline antibody gene sequences. Forexample, germline DNA sequences for murine heavy and light chainvariable region genes can be found in the IMGT (internationalImMunoGeneTics) murine germline sequence database (available athypertext transfer protocol//www.imgt.cines.fr/?), as well as in Kabat,E. A., et al. (1991) Sequences of Proteins of Immunological Interest,Fifth Edition, US Department of Health and Human Services, NIHPublication No. 91-3242; the contents of each of which are expresslyincorporated herein by reference. As another example, the germline DNAsequences for murine heavy and light chain variable region genes can befound in the Genbank database.

Antibody protein sequences are compared against a compiled proteinsequence database using one of the sequence similarity searching methodscalled the Gapped BLAST [Altschul et al. (1997) Nucleic Acids Research25:3389-3402], which is well known to those skilled in the art. BLAST isa heuristic algorithm in that a statistically significant alignmentbetween the antibody sequence and the database sequence is likely tocontain high-scoring segment pairs (HSP) of aligned words. Segment pairswhose scores cannot be improved by extension or trimming is called ahit. Briefly, the nucleotide sequences in the database are translatedand the region between and including FR1 through FR3 framework region isretained. The database sequences have an average length of 98 residues.Duplicate sequences which are exact matches over the entire length ofthe protein are removed. A BLAST search for proteins using the programblastp with default, standard parameters except the low complexityfilter, which is turned off, and the substitution matrix of BLOSUM62,filters for top 5 hits yielding sequence matches. The nucleotidesequences are translated in all six frames and the frame with no stopcodons in the matching segment of the database sequence is consideredthe potential hit. This is in turn confirmed using the BLAST programtblastx, which translates the antibody sequence in all six frames andcompares those translations to the nucleotide sequences in the databasedynamically translated in all six frames.

The identities are exact amino acid matches between the antibodysequence and the protein database over the entire length of thesequence. The positives (identities+substitution match) are notidentical but amino acid substitutions guided by the BLOSUM62substitution matrix. If the antibody sequence matches two of thedatabase sequences with same identity, the hit with most positives wouldbe decided to be the matching sequence hit.

Preferred framework sequences for use in the antibodies of the inventionare those that are structurally similar to the framework sequences usedby selected antibodies of the invention, e.g., similar to the V_(H) 1-80framework sequence, the V_(H) 1-39 framework sequence, the V_(K) 4-74framework sequence and/or the V_(K) 4-55 framework sequences used bypreferred monoclonal antibodies of the invention. The V_(H) CDR1, CDR2,and CDR3 sequences, and the V_(K) CDR1, CDR2, and CDR3 sequences, can begrafted onto framework regions that have the identical sequence as thatfound in the germline immunoglobulin gene from which the frameworksequence derive, or the CDR sequences can be grafted onto frameworkregions that contain one or more mutations as compared to the germlinesequences. For example, it has been found that in certain instances itis beneficial to mutate residues within the framework regions tomaintain or enhance the antigen binding ability of the antibody (see,e.g., U.S. Pat. Nos. 5,530,101; 5,585,089; 5,693,762 and 6,180,370 toQueen et al.).

Another type of variable region modification is to mutate amino acidresidues within the V_(H) and/or V_(K) CDR1, CDR2 and/or CDR3 regions tothereby improve one or more binding properties (e.g. affinity) of theantibody of interest. Site-directed mutagenesis or PCR-mediatedmutagenesis can be performed to introduce the mutation(s) and the effecton antibody binding, or other functional property of interest, can beevaluated in in vitro or in vivo assays as described herein and providedin the Examples. In some embodiments, conservative modifications (asdiscussed above) are introduced. Alternatively, non-conservativemodifications can be made. The mutations may be amino acidsubstitutions, additions or deletions, but are preferably substitutions.Moreover, typically no more than one, two, three, four or five residueswithin a CDR region are altered, although as will be appreciated bythose in the art, variants in other areas (framework regions forexample) can be greater.

Accordingly, in another embodiment, the instant disclosure providesisolated anti-BST1 monoclonal antibodies, or antigen binding portionsthereof, comprising a heavy chain variable region comprising: (a) aV_(H) CDR1 region comprising an amino acid sequence selected from thegroup consisting of SEQ ID NOs: 10, 9 and 56 or an amino acid sequencehaving one, two, three, four or five amino acid substitutions, deletionsor additions as compared to SEQ ID NOs: 10, 9 and 56; (b) a V_(H) CDR2region comprising an amino acid sequence selected from the groupconsisting of SEQ ID NOs: 12 or 51, 11 and 57, or an amino acid sequencehaving one, two, three, four or five amino acid substitutions, deletionsor additions as compared to SEQ ID NOs: 12 or 51, 11 and 57; (c) a V_(H)CDR3 region comprising an amino acid sequence selected from the groupconsisting of SEQ ID NOs: 14, 13 and 58, or an amino acid sequencehaving one, two, three, four or five amino acid substitutions, deletionsor additions as compared to SEQ ID NOs: 14, 13 and 58; (d) a V_(K) CDR1region comprising an amino acid sequence selected from the groupconsisting of SEQ ID NOs: 16, 15 and 59, or an amino acid sequencehaving one, two, three, four or five amino acid substitutions, deletionsor additions as compared to SEQ ID NOs: 16, 15 and 59; (e) a V_(K) CDR2region comprising an amino acid sequence selected from the groupconsisting of SEQ ID NOs: 18, 17 and 60, or an amino acid sequencehaving one, two, three, four or five amino acid substitutions, deletionsor additions as compared to SEQ ID NOs: 18, 17 and 60; and (f) a V_(K)CDR3 region comprising an amino acid sequence selected from the groupconsisting of SEQ ID NOs: 20, 19 and 61, or an amino acid sequencehaving one, two, three, four or five amino acid substitutions, deletionsor additions as compared to SEQ ID NOs: 20, 19 and 61.

Engineered antibodies of the disclosure include those in whichmodifications have been made to framework residues within V_(H) and/orV_(K), e.g. to improve the properties of the antibody. Typically suchframework modifications are made to decrease the immunogenicity of theantibody. For example, one approach is to “backmutate” one or moreframework residues to the corresponding germline sequence. Morespecifically, an antibody that has undergone somatic mutation maycontain framework residues that differ from the germline sequence fromwhich the antibody is derived. Such residues can be identified bycomparing the antibody framework sequences to the germline sequencesfrom which the antibody is derived.

Another type of framework modification involves mutating one or moreresidues within the framework region, or even within one or more CDRregions, to remove T cell epitopes to thereby reduce the potentialimmunogenicity of the antibody. This approach is also referred to as“deimmunization” and is described in further detail in US PatentPublication No. 2003/0153043.

In addition or alternative to modifications made within the framework orCDR regions, antibodies of the invention may be engineered to includemodifications within the Fc region, typically to alter one or morefunctional properties of the antibody, such as serum half-life,complement fixation, Fc receptor binding, and/or antigen-dependentcellular cytotoxicity. Furthermore, an antibody of the invention may bechemically modified (e.g. one or more chemical moieties can be attachedto the antibody) or be modified to alter its glycosylation, again toalter one or more functional properties of the antibody. Each of theseembodiments is described in further detail below. The numbering ofresidues in the Fc region is that of the EU index of Kabat.

In one embodiment, the hinge region of C_(H)1 is modified such that thenumber of cysteine residues in the hinge region is altered, e.g.increased or decreased. This approach is described further in U.S. Pat.No. 5,677,425. The number of cysteine residues in the hinge region ofC_(H)1 is altered to, for example, facilitate assembly of the light andheavy chains or to increase or decrease the stability of the antibody.

In another embodiment, the Fc hinge region of an antibody is mutated todecrease the biological half life of the antibody. More specifically,one or more amino acid mutations are introduced into the C_(H)2-C_(H)3domain interface region of the Fc-hinge fragment such that the antibodyhas impaired Staphylococcal protein A (SpA) binding relative to nativeFc-hinge domain SpA binding. This approach is described in furtherdetail in U.S. Pat. No. 6,165,745.

In another embodiment, the antibody is modified to increase itsbiological half life. Various approaches are possible. For example, oneor more of the following mutations can be introduced: T252L, T254S,T256F, as described in U.S. Pat. No. 6,277,375. Alternatively, toincrease the biological half life, the antibody can be altered withinthe C_(H)1 or C_(L) region to contain a salvage receptor binding epitopetaken from two loops of a C_(H)2 domain of an Fc region of an IgG, asdescribed in U.S. Pat. Nos. 5,869,046 and 6,121,022.

In another embodiment, the antibody is produced as a Unibody® asdescribed in WO2007/059782 which is incorporated herein by reference inits entirety.

In yet other embodiments, the Fc region is altered by replacing at leastone amino acid residue with a different amino acid residue to alter theeffector function(s) of the antibody. For example, one or more aminoacids selected from amino acid residues 234, 235, 236, 237, 297, 318,320 and 322 can be replaced with a different amino acid residue suchthat the antibody has an altered affinity for an effector ligand butretains the antigen-binding ability of the parent antibody. The effectorligand to which affinity is altered can be, for example, an Fc receptoror the C1 component of complement. This approach is described in furtherdetail in U.S. Pat. Nos. 5,624,821 and 5,648,260.

In another example, one or more amino acids selected from amino acidresidues 329, 331 and 322 can be replaced with a different amino acidresidue such that the antibody has altered Clq binding and/or reduced orabolished complement dependent cytotoxicity (CDC). This approach isdescribed in further detail in U.S. Pat. No. 6,194,551.

In another example, one or more amino acid residues within amino acidpositions 231 and 239 are altered to thereby alter the ability of theantibody to fix complement. This approach is described further in PCTPublication WO 94/29351.

In yet another example, the Fc region is modified to increase theability of the antibody to mediate antibody dependent cellularcytotoxicity (ADCC) and/or to increase the affinity of the antibody foran Fcγ receptor by modifying one or more amino acids at the followingpositions: 238, 239, 248, 249, 252, 254, 255, 256, 258, 265, 267, 268,269, 270, 272, 276, 278, 280, 283, 285, 286, 289, 290, 292, 293, 294,295, 296, 298, 301, 303, 305, 307, 309, 312, 315, 320, 322, 324, 326,327, 329, 330, 331, 333, 334, 335, 337, 338, 340, 360, 373, 376, 378,382, 388, 389, 398, 414, 416, 419, 430, 434, 435, 437, 438 or 439. Thisapproach is described further in PCT Publication WO 00/42072 by Presta.Moreover, the binding sites on human IgG1 for FcγR1, FcγRII, FcγRIII andFcRn have been mapped and variants with improved binding have beendescribed (see Shields, R. L. et al. (2001) J. Biol. Chem.276:6591-6604). Specific mutations at positions 256, 290, 298, 333, 334and 339 were shown to improve binding to FcγRIII. Additionally, thefollowing combination mutants were shown to improve FcγRIII binding:T256A/S298A, S298A/E333A, S298A/K224A and S298A/E333A/K334A. FurtherADCC variants are described for example in WO2006/019447.

In yet another example, the Fc region is modified to increase thehalf-life of the antibody, generally by increasing binding to the FcRnreceptor, as described for example in PCT/US2008/088053, U.S. Pat. No.7,371,826, U.S. Pat. No. 7,670,600 and WO 97/34631. In anotherembodiment, the antibody is modified to increase its biological halflife. Various approaches are possible. For example, one or more of thefollowing mutations can be introduced: T252L, T254S, T256F, as describedin U.S. Pat. No. 6,277,375 by Ward. Alternatively, to increase thebiological half life, the antibody can be altered within the C_(H)1 orC_(L) region to contain a salvage receptor binding epitope taken fromtwo loops of a C_(H)2 domain of an Fc region of an IgG, as described inU.S. Pat. Nos. 5,869,046 and 6,121,022.

In still another embodiment, the glycosylation of an antibody ismodified. For example, an aglycoslated antibody can be made (i.e. theantibody that lacks glycosylation). Glycosylation can be altered to, forexample, increase the affinity of the antibody for antigen. Suchcarbohydrate modifications can be accomplished by, for example, alteringone or more sites of glycosylation within the antibody sequence. Forexample, one or more amino acid substitutions can be made that result inelimination of one or more variable region framework glycosylation sitesto thereby eliminate glycosylation at that site. Such aglycosylation mayincrease the affinity of the antibody for antigen. Such an approach isdescribed in further detail in U.S. Pat. Nos. 5,714,350 and 6,350,861 byCo et al., and can be accomplished by removing the asparagine atposition 297.

Additionally or alternatively, an antibody can be made that has analtered type of glycosylation, such as a hypofucosylated antibody havingreduced amounts of fucosyl residues or an antibody having increasedbisecting GlcNac structures. This is sometimes referred to in the art asan “engineered glycoform”. Such altered glycosylation patterns have beendemonstrated to increase the ADCC ability of antibodies. Suchcarbohydrate modifications can generally be accomplished in two ways;for example, in some embodiments, the antibody is expressed in a hostcell with altered glycosylation machinery. Cells with alteredglycosylation machinery have been described in the art and can be usedas host cells in which to express recombinant antibodies of theinvention to thereby produce an antibody with altered glycosylation.Reference is made to the POTELLIGENT® technology. For example, the celllines Ms704, Ms705, and Ms709 lack the fucosyltransferase gene, FUT8(alpha (1,6) fucosyltransferase), such that antibodies expressed in theMs704, Ms705, and Ms709 cell lines lack fucose on their carbohydrates.The Ms704, Ms705, and Ms709 FUT8^(−/−) cell lines were created by thetargeted disruption of the FUT8 gene in CHO/DG44 cells using tworeplacement vectors [see US Patent Publication No. 2004/0110704, U.S.Pat. No. 7,517,670 and Yamane-Ohnuki et al. (2004) Biotechnol. Bioeng.87:614-22]. As another example, EP 1,176,195 by Hanai et al. describes acell line with a functionally disrupted FUT8 gene, which encodes afucosyl transferase, such that antibodies expressed in such a cell lineexhibit hypofucosylation by reducing or eliminating the alpha 1,6bond-related enzyme. Hanai et al. also describe cell lines which have alow enzyme activity for adding fucose to the N-acetylglucosamine thatbinds to the Fc region of the antibody or does not have the enzymeactivity, for example the rat myeloma cell line YB2/0 (ATCC CRL 1662).Alternatively, engineered glycoforms, particularly afucosylation, can bedone using small molecule inhibitors of glycosylation pathway enzymes[see, for example, Rothman et al. (1989) Mol. Immunol. 26(12):113-1123;Elbein (1991) FASEB J. 5:3055; PCT/US2009/042610 and U.S. Pat. No.7,700,321]. PCT Publication WO 03/035835 describes a variant CHO cellline, Lec13 cells, with reduced ability to attach fucose toAsn(297)-linked carbohydrates, also resulting in hypofucosylation ofantibodies expressed in that host cell [see also Shields, R. L. et al.(2002) J. Biol. Chem. 277:26733-26740]. PCT Publication WO 99/54342describes cell lines engineered to express glycoprotein-modifyingglycosyl transferases (e.g. beta(1,4)-N-acetylglucosaminyltransferaseIII (GnTIII)) such that antibodies expressed in the engineered celllines exhibit increased bisecting GlcNac structures which results inincreased ADCC activity of the antibodies [see also Umana et al. (1999)Nat. Biotech. 17:176-180].

Alternatively, the fucose residues of the antibody may be cleaved offusing a fucosidase enzyme. For example, the fucosidasealpha-L-fucosidase removes fucosyl residues from antibodies [Tarentino,A. L. et al. (1975) Biochem. 14:5516-23].

Another modification of the antibodies herein that is contemplated bythe invention is pegylation. An antibody can be pegylated to, forexample, increase the biological (e.g. serum) half life of the antibody.To pegylate an antibody, the antibody, or fragment thereof, typically isreacted with polyethylene glycol (PEG), such as a reactive ester oraldehyde derivative of PEG, under conditions in which one or more PEGgroups become attached to the antibody or antibody fragment. Preferably,the pegylation is carried out via an acylation reaction or an alkylationreaction with a reactive PEG molecule (or an analogous reactivewater-soluble polymer). As used herein, the term “polyethylene glycol”is intended to encompass any of the forms of PEG that have been used toderivatize other proteins, such as mono (C1-C10) alkoxy- oraryloxy-polyethylene glycol or polyethylene glycol-maleimide. In certainembodiments, the antibody to be pegylated is an aglycosylated antibody.Methods for pegylating proteins are known in the art and can be appliedto the antibodies of the invention. See, for example, EP 0154316 and EP0401384.

In additional embodiments, for example in the use of the antibodies ofthe invention for diagnostic or detection purposes, the antibodies maycomprise a label. By “labeled” herein is meant that a compound has atleast one element, isotope or chemical compound attached to enable thedetection of the compound. In general, labels fall into three classes:a) isotopic labels, which may be radioactive or heavy isotopes; b)magnetic, electrical, thermal; and c) colored or luminescent dyes;although labels include enzymes and particles such as magnetic particlesas well. Preferred labels include, but are not limited to, fluorescentlanthanide complexes (including those of Europium and Terbium), andfluorescent labels including, but not limited to, quantum dots,fluorescein, rhodamine, tetramethylrhodamine, eosin, erythrosin,coumarin, methyl-coumarins, pyrene, Malacite green, stilbene, LuciferYellow, Cascade Blue, Texas Red, the Alexa dyes, the Cy dyes, and othersdescribed in the 6th Edition of the Molecular Probes Handbook by RichardP. Haugland, hereby expressly incorporated by reference.

Linkers

The present invention provides antibody-partner conjugates where theantibody is linked to the partner through a chemical linker. In someembodiments, the linker is a peptidyl linker, other linkers includehydrazine and disulfide linkers. In addition to the linkers as beingattached to the partner, the present disclosure also provides cleavablelinker arms that are appropriate for attachment to essentially anymolecular species. The linker arm aspect of the invention is exemplifiedherein by reference to their attachment to a therapeutic moiety. Itwill, however, be readily apparent to those of skill in the art that thelinkers can be attached to diverse species including, but not limitedto, diagnostic agents, analytical agents, biomolecules, targetingagents, detectable labels and the like.

The use of peptidyl and other linkers in antibody-partner conjugates isdescribed in U.S. Provisional Patent Application Ser. Nos. 60/295,196;60/295,259; 60/295,342; 60/304,908; 60/572,667; 60/661,174; 60/669,871;60/720,499; 60/730,804; and 60/735,657 and U.S. patent application Ser.Nos. 10/160,972; 10/161,234; 11/134,685; 11/134,826; and 11/398,854 andU.S. Pat. No. 6,989,452 and PCT Patent Application No. PCT/US2006/37793,all of which are incorporated herein by reference. Additional linkersare described in U.S. Pat. No. 6,214,345, US Patent Application2003/0096743 and US Patent Application 2003/0130189, de Groot et al, J.Med. Chem. 42, 5277 (1999); de Groot et al. J. Org. Chem. 43, 3093(2000); de Groot et al., J. Med. Chem. 66, 8815, (2001); WO 02/083180;Carl et al., J. Med. Chem. Lett. 24, 479, (1981); Dubowchik et al.,Bioorg & Med. Chem. Lett. 8, 3347 (1998); and U.S. Provisional PatentApplication Ser. No. 60/891,028.

In one aspect, the present disclosure relates to linkers that are usefulto attach targeting groups to therapeutic agents and markers. In anotheraspect, this disclosure provides linkers that impart stability tocompounds, reduce their in vivo toxicity, or otherwise favorably affecttheir pharmacokinetics, bioavailability and/or pharmacodynamics. It isgenerally preferred that in such embodiments, the linker is cleaved,releasing the active drug, once the drug is delivered to its site ofaction. Thus, in one embodiment, the linkers of the present inventionare traceless, such that once removed from the therapeutic agent ormarker (such as during activation), no trace of the linker's presenceremains. In another embodiment, the linkers are characterized by theirability to be cleaved at a site in or near the target cell such as atthe site of therapeutic action or marker activity. Such cleavage can beenzymatic in nature. This feature aids in reducing systemic activationof the therapeutic agent or marker, reducing toxicity and systemic sideeffects. Preferred cleavable groups for enzymatic cleavage includepeptide bonds, ester linkages, and disulfide linkages. In otherembodiments, the linkers are sensitive to pH and are cleaved throughchanges in pH.

An aspect of the current disclosure is the ability to control the speedwith which the linkers cleave. Often a linker that cleaves quickly isdesired. In some embodiments, however, a linker that cleaves more slowlymay be preferred. For example, in a sustained release formulation or ina formulation with both a quick release and a slow release component, itmay be useful to provide a linker which cleaves more slowly. WO02/096910 provides several specific ligand-drug complexes having ahydrazine linker. However, there is no way to “tune” the linkercomposition dependent upon the rate of cyclization required, and theparticular compounds described cleave the ligand from the drug at aslower rate than is preferred for many drug-linker conjugates. Incontrast, the hydrazine linkers of the current invention provide for arange of cyclization rates, from very fast to very slow, therebyallowing for the selection of a particular hydrazine linker based on thedesired rate of cyclization.

For example, very fast cyclization can be achieved with hydrazinelinkers that produce a single 5-membered ring upon cleavage. Preferredcyclization rates for targeted delivery of a cytotoxic agent to cellsare achieved using hydrazine linkers that produce, upon cleavage, eithertwo 5-membered rings or a single 6-membered ring resulting from a linkerhaving two methyls at the geminal position. The gem-dimethyl effect hasbeen shown to accelerate the rate of the cyclization reaction ascompared to a single 6-membered ring without the two methyls at thegeminal position. This results from the strain being relieved in thering. Sometimes, however, substitutents may slow down the reactioninstead of making it faster. Often the reasons for the retardation canbe traced to steric hindrance. For example, the gem dimethylsubstitution allows for a much faster cyclization reaction to occurcompared to when the geminal carbon is a CH₂.

It is important to note, however, that in some embodiments, a linkerthat cleaves more slowly may be preferred. For example, in a sustainedrelease formulation or in a formulation with both a quick release and aslow release component, it may be useful to provide a linker whichcleaves more slowly. In certain embodiments, a slow rate of cyclizationis achieved using a hydrazine linker that produces, upon cleavage,either a single 6-membered ring, without the gem-dimethyl substitution,or a single 7-membered ring. The linkers also serve to stabilize thetherapeutic agent or marker against degradation while in circulation.This feature provides a significant benefit since such stabilizationresults in prolonging the circulation half-life of the attached agent ormarker. The linker also serves to attenuate the activity of the attachedagent or marker so that the conjugate is relatively benign while incirculation and has the desired effect, for example is toxic, afteractivation at the desired site of action. For therapeutic agentconjugates, this feature of the linker serves to improve the therapeuticindex of the agent.

The stabilizing groups are preferably selected to limit clearance andmetabolism of the therapeutic agent or marker by enzymes that may bepresent in blood or non-target tissue and are further selected to limittransport of the agent or marker into the cells. The stabilizing groupsserve to block degradation of the agent or marker and may also act inproviding other physical characteristics of the agent or marker. Thestabilizing group may also improve the agent or marker's stabilityduring storage in either a formulated or non-formulated form.

Ideally, the stabilizing group is useful to stabilize a therapeuticagent or marker if it serves to protect the agent or marker fromdegradation when tested by storage of the agent or marker in human bloodat 37° C. for 2 hours and results in less than 20%, preferably less than10%, more preferably less than 5% and even more preferably less than 2%,cleavage of the agent or marker by the enzymes present in the humanblood under the given assay conditions. The present invention alsorelates to conjugates containing these linkers. More particularly, theinvention relates to the use of prodrugs that may be used for thetreatment of disease, especially for cancer chemotherapy. Specifically,use of the linkers described herein provide for prodrugs that display ahigh specificity of action, a reduced toxicity, and an improvedstability in blood relative to prodrugs of similar structure. Thelinkers of the present disclosure as described herein may be present ata variety of positions within the partner molecule.

Thus, there is provided a linker that may contain any of a variety ofgroups as part of its chain that will cleave in vivo, e.g. in the bloodstream, at a rate which is enhanced relative to that of constructs thatlack such groups. Also provided are conjugates of the linker arms withtherapeutic and diagnostic agents. The linkers are useful to formprodrug analogs of therapeutic agents and to reversibly link atherapeutic or diagnostic agent to a targeting agent, a detectablelabel, or a solid support. The linkers may be incorporated intocomplexes that include cytotoxins.

The attachment of a prodrug to an antibody may give additional safetyadvantages over conventional antibody conjugates of cytotoxic drugs.Activation of a prodrug may be achieved by an esterase, both withintumor cells and in several normal tissues, including plasma. The levelof relevant esterase activity in humans has been shown to be verysimilar to that observed in rats and non-human primates, although lessthan that observed in mice. Activation of a prodrug may also be achievedby cleavage by glucuronidase. In addition to the cleavable peptide,hydrazine, or disulfide group, one or more self-immolative linker groupsare optionally introduced between the cytotoxin and the targeting agent.These linker groups may also be described as spacer groups and containat least two reactive functional groups. Typically, one chemicalfunctionality of the spacer group bonds to a chemical functionality ofthe therapeutic agent, e.g. cytotoxin, while the other chemicalfunctionality of the spacer group is used to bond to a chemicalfunctionality of the targeting agent or the cleavable linker. Examplesof chemical functionalities of spacer groups include hydroxy, mercapto,carbonyl, carboxy, amino, ketone, and mercapto groups.

The self-immolative linkers are generally a substituted or unsubstitutedalkyl, substituted or unsubstituted aryl, substituted or unsubstitutedheteroaryl or substituted or unsubstituted heteroalkyl group. In oneembodiment, the alkyl or aryl groups may comprise between 1 and 20carbon atoms. They may also comprise a polyethylene glycol moiety.

Exemplary spacer groups include, for example, 6-aminohexanol,6-mercaptohexanol, 10-hydroxydecanoic acid, glycine and other aminoacids, 1,6-hexanediol, β-alanine, 2-ammoethanol, cysteamine(2-aminoethanethiol), 5-aminopentanoic acid, 6-aminohexanoic acid,3-maleimidobenzoic acid, phthalide, α-substituted phthalies, thecarbonyl group, animal esters, nucleic acids, peptides and the like.

The spacer can serve to introduce additional molecular mass and chemicalfunctionality into the cytotoxin-targeting agent complex. Generally, theadditional mass and functionality will affect the serum half-life andother properties of the complex. Thus, through careful selection ofspacer groups, cytotoxin complexes with a range of serum half-lives canbe produced.

When multiple spacers are present, either identical or different spacersmay be used.

Additional linker moiety may be used that preferably imparts increasedsolubility or decreased aggregation properties to conjugates utilizing alinker that contains the moiety or modifies the hydrolysis rate of theconjugate, such linkers do not have to be self immolative. In oneembodiment, the linking moiety is substituted alkyl, unsubstitutedalkyl, substituted aryl, unsubstituted aryl, substituted heteroalkyl, orunsubstituted heteroalkyl, any of which may be straight, branched, orcyclic. The substitutions may be, for example, a lower (C₁-C₆) alkyl,alkoxy, alkylthio, alkylamino, or dialkylamino. In certain embodiments,linkers comprise a non-cyclic moiety. In another embodiment, linkerscomprise any positively or negatively charged amino acid polymer, suchas polylysine or polyargenine. Linkers can comprise a polymer such as apolyethylene glycol moiety. Additionally the linker can comprise, forexample, both a polymer component and a small chemical moiety. In apreferred embodiment, such linkers comprise a polyethylene glycol (PEG)moiety.

The PEG portion may be between 1 and 50 units long. Preferably, the PEGwill have 1-12 repeat units, more preferably 3-12 repeat units, morepreferably 2-6 repeat units, or even more preferably 3-5 repeat unitsand most preferably 4 repeat units. A linker may consist solely of thePEG moiety, or it may also contain an additional substituted orunsubstituted alkyl or heteroalkyl. It is useful to combine PEG as partof the moiety to enhance the water solubility of the complex.Additionally, the PEG moiety reduces the degree of aggregation that mayoccur during the conjugation of the drug to the antibody.

For further discussion of types of cytotoxins, linkers and other methodsfor conjugating therapeutic agents to antibodies, see also PCTPublication WO 2007/059404 to Gangwar et al. and entitled “CytotoxicCompounds And Conjugates,” Saito, G. et al. (2003) Adv. Drug Deliv. Rev.55:199-215; Trail, P. A. et al. (2003) Cancer Immunol. Immunother.52:328-337; Payne, G. (2003) Cancer Cell 3:207-212; Allen, T. M. (2002)Nat. Rev. Cancer 2:750-763; Pastan, I. and Kreitman, R. J. (2002) Curr.Opin. Investig. Drugs 3:1089-1091; Senter, P. D. and Springer, C J.(2001) Adv. Drag Deliv. Rev. 53:247-264, each of which is herebyincorporated by reference in their entirety.

Partner Molecules

The present invention includes an antibody conjugated to a partnermolecule, such as a cytotoxin, a drug (e.g. an immunosuppressant) or aradiotoxin. Such conjugates are also referred to herein as“immunoconjugates.” Immunoconjugates that include one or more cytotoxinsare referred to as “immunotoxins.” A cytotoxin or cytotoxic agentincludes any agent that is detrimental to (e.g. kills) cells.

Examples of partner molecules of the present disclosure include taxol,cytochalasin B, gramicidin D, ethidium bromide, emetine, mitomycin,etoposide, tenoposide, vincristine, vinblastine, colchicin, doxorubicin,daunorubicin, dihydroxy anthracin dione, mitoxantrone, mithramycin,actinomycin D, 1-dehydrotestosterone, glucocorticoids, procaine,tetracaine, lidocaine, propranolol, and puromycin and analogs orhomologs thereof. Examples of partner molecules also include, forexample, antimetabolites (e.g. methotrexate, 6-mercaptopurine,6-thioguanine, cytarabine, 5-fluorouracil decarbazine), alkylatingagents (e.g. mechlorethamine, thioepa chlorambucil, melphalan,carmustine (BSNU) and lomustine (CCNU), cyclothosphamide, busulfan,dibromomannitol, streptozotocin, mitomycin C, and cis-dichlorodiamineplatinum (II) (DDP) cisplatin), anthracyclines (e.g. daunorubicin(formerly daunomycin) and doxorubicin), antibiotics (e.g. dactinomycin(formerly actinomycin), bleomycin, mithramycin, and anthramycin (AMC)),and anti-mitotic agents (e.g. vincristine and vinblastine).

Other preferred examples of partner molecules that can be conjugated toan antibody of the invention include duocarmycins, calicheamicins,maytansines and auristatins, and derivatives thereof. An example of acalicheamicin antibody conjugate is commercially available (Mylotarg®;American Home Products).

Preferred examples of partner molecule are CC-1065 and the duocarmycins.CC-1065 was first isolated from Streptomyces zelensis in 1981 by theUpjohn Company (Hanka et al, J. Antibiot. 31: 1211 (1978); Martin etal., J. Antibiot. 33: 902 (1980); Martin et al., J. Antibiot. 34: 1119(1981)) and was found to have potent antitumor and antimicrobialactivity both in vitro and in experimental animals (Li et al., CancerRes. 42: 999 (1982)). CC-1065 binds to double-stranded B-DNA within theminor groove (Swenson et al., Cancer Res. 42: 2821 (1982)) with thesequence preference of 5′-d(A/GNTTA)-3′ and 5′-d(AAAAA)-3′ and alkylatesthe N3 position of the 3′-adenine by its CPI left-hand unit present inthe molecule (Hurley et al., Science 226: 843 (1984)).

Despite its potent and broad antitumor activity, CC-1065 cannot be usedin humans because it causes delayed death in experimental animals. Manyanalogues and derivatives of CC-1065 and the duocarmycins are known inthe art. The research into the structure, synthesis and properties ofmany of the compounds has been reviewed. See, for example, Boger et al.,Angew. Chem. Int. Ed. Engl. 35: 1438 (1996); and Boger et al., Chem.Rev. 97: 787 (1997). A group at Kyowa Hakko Kogya Co., Ltd. has prepareda number of CC-1065 derivatives. See, for example, U.S. Pat. Nos.5,101,038; 5,641,780; 5,187,186; 5,070,092; 5,703,080; 5,070,092;5,641,780; 5,101,038; and 5,084,468; and published PCT application, WO96/10405 and published European application 0 537 575 A1. The UpjohnCompany (Pharmacia Upjohn) has also been active in preparing derivativesof CC-1065. See, for example, U.S. Pat. Nos. 5,739,350; 4,978,757,5,332, 837 and 4,912,227.

Antibody Physical Properties

The antibodies of the present invention may be further characterized bythe various physical properties of the anti-BST1 antibodies. Variousassays may be used to detect and/or differentiate different classes ofantibodies based on these physical properties.

In some embodiments, antibodies of the present invention may contain oneor more glycosylation sites in either the light or heavy chain variableregion. The presence of one or more glycosylation sites in the variableregion may result in increased immunogenicity of the antibody or analteration of the pK of the antibody due to altered antigen binding[Marshall et al (1972) Annu Rev Biochem 41:673-702; Gala F A andMorrison S L (2004) J Immunol 172:5489-94; Wallick et al (1988) J ExpMed 168:1099-109; Spiro R G (2002) Glycobiology 12:43R-56R; Parekh et al(1985) Nature 316:452-7; Mimura et al. (2000) Mol Immunol 37:697-706].Glycosylation has been known to occur at motifs containing an N—X—S/Tsequence. Variable region glycosylation may be tested using a glycoblotassay, which cleaves the antibody to produce a Fab, and then tests forglycosylation using an assay that measures periodate oxidation andSchiff base formation. Alternatively, variable region glycosylation maybe tested using Dionex light chromatography (Dionex-LC), which cleavessaccharides from a Fab into monosaccharides and analyzes the individualsaccharide content. In some instances, it is preferred to have ananti-BST1 antibody that does not contain variable region glycosylation.This can be achieved either by selecting antibodies that do not containthe glycosylation motif in the variable region or by mutating residueswithin the glycosylation motif using standard techniques well known inthe art.

In a preferred embodiment, the antibodies of the present invention donot contain asparagine isomerism sites. A deamidation or isoasparticacid effect may occur on N-G or D-G sequences, respectively. Thedeamidation or isoaspartic acid effect results in the creation ofisoaspartic acid which decreases the stability of an antibody bycreating a kinked structure off a side chain carboxy terminus ratherthan the main chain. The creation of isoaspartic acid can be measuredusing an iso-quant assay, which uses a reverse-phase HPLC to test forisoaspartic acid.

Each antibody will have a unique isoelectric point (pI), but generallyantibodies will fall in the pH range of between 6 and 9.5. The pI for anIgG1 antibody typically falls within the pH range of 7-9.5 and the pIfor an IgG4 antibody typically falls within the pH range of 6-8.Antibodies may have a pI that is outside this range. Although theeffects are generally unknown, there is speculation that antibodies witha pI outside the normal range may have some unfolding and instabilityunder in vivo conditions. The isoelectric point may be tested using acapillary isoelectric focusing assay, which creates a pH gradient andmay utilize laser focusing for increased accuracy [Janini et al (2002)Electrophoresis 23:1605-11; Ma et al. (2001) Chromatographia 53:S75-89;Hunt et al (1998) J Chromatogr A 800:355-67]. In some instances, it ispreferred to have an anti-BST1 antibody that contains a pI value thatfalls in the normal range. This can be achieved either by selectingantibodies with a pI in the normal range, or by mutating charged surfaceresidues using standard techniques well known in the art.

Each antibody will have a melting temperature that is indicative ofthermal stability [Krishnamurthy R and Manning M C (2002) Curr PharmBiotechnol 3:361-71]. A higher thermal stability indicates greateroverall antibody stability in vivo. The melting point of an antibody maybe measured using techniques such as differential scanning calorimetry[Chen et al. (2003) Pharm Res 20:1952-60; Ghirlando et al. (1999)Immunol Lett 68:47-52]. T_(M1) indicates the temperature of the initialunfolding of the antibody. T_(M2) indicates the temperature of completeunfolding of the antibody. Generally, it is preferred that the T_(M1) ofan antibody of the present invention is greater than 60° C., preferablygreater than 65° C., even more preferably greater than 70° C.Alternatively, the thermal stability of an antibody may be measure usingcircular dichroism [Murray et al. (2002) J. Chromatogr Sci 40:343-9].

In a preferred embodiment, antibodies are selected that do not rapidlydegrade. Fragmentation of an anti-BST1 antibody may be measured usingcapillary electrophoresis (CE) and MALDI-MS, as is well understood inthe art [Alexander A J and Hughes D E (1995) Anal. Chem. 67:3626-32].

In another preferred embodiment, antibodies are selected that haveminimal aggregation effects. Aggregation may lead to triggering of anunwanted immune response and/or altered or unfavorable pharmacokineticproperties. Generally, antibodies are acceptable with aggregation of 25%or less, preferably 20% or less, even more preferably 15% or less, evenmore preferably 10% or less and even more preferably 5% or less.Aggregation may be measured by several techniques well known in the art,including size-exclusion column (SEC) high performance liquidchromatography (HPLC), and light scattering to identify monomers,dimers, trimers or multimers.

Methods of Engineering Antibodies

As discussed above, the anti-BST1 antibodies having V_(H) and V_(K)sequences disclosed herein can be used to create new anti-BST1antibodies by modifying the V_(H) and/or V_(K) sequences, or theconstant region(s) attached thereto. Thus, in another aspect of theinvention, the structural features of an anti-BST1 antibody of theinvention, e.g. BST1_A2, BST1_A1 or BST1_A3, are used to createstructurally related anti-BST1 antibodies that retain at least onefunctional property of the antibodies of the invention, such as bindingto the human BST1. For example, one or more CDR regions of BST1_A2,BST1_A1 or BST1_A3, or mutations thereof, can be combined recombinantlywith known framework regions and/or other CDRs to create additional,recombinantly-engineered, anti-BST1 antibodies of the invention, asdiscussed above. Other types of modifications include those described inthe previous section. The starting material for the engineering methodis one or more of the V_(H) and/or V_(K) sequences provided herein, orone or more CDR regions thereof. To create the engineered antibody, itis not necessary to actually prepare (i.e. express as a protein) anantibody having one or more of the V_(H) and/or V_(K) sequences providedherein, or one or more CDR regions thereof. Rather, the informationcontained in the sequence(s) is used as the starting material to createa “second generation” sequence(s) derived from the original sequence(s)and then the “second generation” sequence(s) is prepared and expressedas a protein.

Accordingly, in another embodiment, the invention provides a method forpreparing an anti-BST1 antibody comprising: providing: (i) a heavy chainvariable region antibody sequence comprising a CDR1 sequence selectedfrom the group consisting of SEQ ID NOs: 10, 9 and 56, a CDR2 sequenceselected from the group consisting of SEQ ID NOs: 12 or 51, 11 and 57,and/or a CDR3 sequence selected from the group consisting of SEQ ID NOs:14, 13 and 58; and/or (ii) a light chain variable region antibodysequence comprising a CDR1 sequence selected from the group consistingof SEQ ID NOs: 16, 15 and 59, a CDR2 sequence selected from the groupconsisting of SEQ ID NOs: 18, 17 and 60 and/or a CDR3 sequence selectedfrom the group consisting of SEQ ID NOs: 20, 19 and 61, altering atleast one amino acid residue within the heavy chain variable regionantibody sequence and/or the light chain variable region antibodysequence to create at least one altered antibody sequence; andexpressing the altered antibody sequence as a protein.

Standard molecular biology techniques can be used to prepare and expressthe altered antibody sequence.

Preferably, the antibody encoded by the altered antibody sequence(s) isone that retains one, some or all of the functional properties of theanti-BST1 antibodies described herein, which functional propertiesinclude, but are not limited to: (a) binds to the human BST1 with aK_(D) of 1×10⁻⁷ M or less; (b) binds to human CHO cells transfected withthe BST1.

The functional properties of the altered antibodies can be assessedusing standard assays available in the art and/or described herein, suchas those set forth in the Examples (e.g. flow cytometry, bindingassays).

In certain embodiments of the methods of engineering antibodies of theinvention, mutations can be introduced randomly or selectively along allor part of an anti-BST1 antibody coding sequence and the resultingmodified anti-BST1 antibodies can be screened for binding activityand/or other functional properties as described herein. Mutationalmethods have been described in the art. For example, PCT Publication WO02/092780 describes methods for creating and screening antibodymutations using saturation mutagenesis, synthetic ligation assembly, ora combination thereof. Alternatively, PCT Publication WO 03/074679describes methods of using computational screening methods to optimizephysiochemical properties of antibodies.

Nucleic Acid Molecules Encoding Antibodies of the Invention

Another aspect of the invention pertains to nucleic acid molecules thatencode the antibodies of the invention. The nucleic acids may be presentin whole cells, in a cell lysate, or in a partially purified orsubstantially pure form. A nucleic acid is “isolated” or “renderedsubstantially pure” when purified away from other cellular components orother contaminants, e.g. other cellular nucleic acids or proteins, bystandard techniques, including alkaline/SDS treatment, CsCl banding,column chromatography, agarose gel electrophoresis and others well knownin the art. See, F. Ausubel, et al., ed. (1987) Current Protocols inMolecular Biology, Greene Publishing and Wiley Interscience, N.Y. Anucleic acid of the invention can be, for example, DNA or RNA and may ormay not contain intronic sequences. In a preferred embodiment, thenucleic acid is a cDNA molecule.

Nucleic acids of the invention can be obtained using standard molecularbiology techniques. For antibodies expressed by hybridomas, cDNAsencoding the light and heavy chains of the antibody made by thehybridoma can be obtained by standard PCR amplification or cDNA cloningtechniques. For antibodies obtained from an immunoglobulin gene library(e.g. using phage display techniques), nucleic acids encoding theantibody can be recovered from the library.

Preferred nucleic acids molecules of the invention are those encodingthe V_(H) and V_(K) sequences of the BST1_A2, BST1_A1 or BST1_A3monoclonal antibodies. DNA sequences encoding the V_(H) sequences ofBST1_A2, BST1_A1 or BST1_A3 are shown in SEQ ID NOs: 6, 5 and 54,respectively. DNA sequences encoding the V_(K) sequences of BST1_A2,BST1_A1 or BST1_A3 are shown in SEQ ID NOs: 8, 7 and 55, respectively.

Other preferred nucleic acids of the invention are nucleic acids havingat least 80% sequence identity, such as at least 85%, at least 90%, atleast 95%, at least 98% or at least 99% sequence identity, with one ofthe sequences shown in SEQ ID NOs: 6, 5, 8, 7, 54 and 55, which nucleicacids encode an antibody of the invention, or an antigen-binding portionthereof.

The percent identity between two nucleic acid sequences is the number ofpositions in the sequence in which the nucleotide is identical, takinginto account the number of gaps and the length of each gap, which needto be introduced for optimal alignment of the two sequences. Thecomparison of sequences and determination of percent identity betweentwo sequences can be accomplished using a mathematical algorithm, suchas the algorithm of Meyers and Miller or the XBLAST program of Altschuldescribed above.

Still further, preferred nucleic acids of the invention comprise one ormore CDR-encoding portions of the nucleic acid sequences shown in SEQ IDNOs: 6, 5, 8, 7, 54 and 55. In this embodiment, the nucleic acid mayencode the heavy and light chain CDR1, CDR2 and/or CDR3 sequence ofBST1_A2, BST1_A1 or BST1_A3.

Nucleic acids which have at least 80%, such as at least 85%, at least90%, at least 95%, at least 98% or at least 99% sequence identity, withsuch a CDR-encoding portion of SEQ ID NOs: 6, 5, 8, 7, 54 and 55 (V_(H)and V_(K) seqs) are also preferred nucleic acids of the invention. Suchnucleic acids may differ from the corresponding portion of SEQ ID NOs:6, 5, 8, 7, 54 and 55 in a non-CDR coding region and/or in a CDR-codingregion. Where the difference is in a CDR-coding region, the nucleic acidCDR region encoded by the nucleic acid typically comprises one or moreconservative sequence modifications as defined herein compared to thecorresponding CDR sequence of BST1_A2, BST1_A1 or BST1_A3.

Once DNA fragments encoding V_(H) and V_(K) segments are obtained, theseDNA fragments can be further manipulated by standard recombinant DNAtechniques, for example, to convert the variable region genes tofull-length antibody chain genes, to Fab fragment genes, or to a scFvgene. In these manipulations, a V_(K)- or V_(H)-encoding DNA fragment isoperatively linked to another DNA fragment encoding another protein,such as an antibody constant region or a flexible linker. The term“operatively linked”, as used in this context, is intended to mean thatthe two DNA fragments are joined such that the amino acid sequencesencoded by the two DNA fragments remain in-frame.

The isolated DNA encoding the V_(H) region can be converted to afull-length heavy chain gene by operatively linking the V_(H)-encodingDNA to another DNA molecule encoding heavy chain constant regions(C_(H)1, C_(H)2 and C_(H)3). The sequences of murine heavy chainconstant region genes are known in the art [see e.g. Kabat, E. A., etal. (1991) Sequences of Proteins of Immunological Interest, FifthEdition, US Department of Health and Human Services, NIH Publication No.91-3242] and DNA fragments encompassing these regions can be obtained bystandard PCR amplification. The heavy chain constant region can be anIgG1, IgG2, IgG3, IgG4, IgA, IgE, IgM or IgD constant region, but mostpreferably is an IgG1 or IgG4 constant region. For a Fab fragment heavychain gene, the V_(H)-encoding DNA can be operatively linked to anotherDNA molecule encoding only the heavy chain C_(H)1 constant region.

The isolated DNA encoding the VL/VK region can be converted to afull-length light chain gene (as well as a Fab light chain gene) byoperatively linking the V_(L)-encoding DNA to another DNA moleculeencoding the light chain constant region, C_(L). The sequences of murinelight chain constant region genes are known in the art [see, e.g. Kabat,E. A., et al. (1991) Sequences of Proteins of Immunological Interest,Fifth Edition, US Department of Health and Human Services, NIHPublication No. 91-3242] and DNA fragments encompassing these regionscan be obtained by standard PCR amplification. In preferred embodiments,the light chain constant region can be a kappa or lambda constantregion.

To create a scFv gene, the V_(H)- and V_(L)/V_(K)-encoding DNA fragmentsare operatively linked to another fragment encoding a flexible linker,e.g. encoding the amino acid sequence (Gly₄-Ser)₃, such that the V_(H)and V_(L)/V_(K) sequences can be expressed as a contiguous single-chainprotein, with the V_(L)/V_(K) and V_(H) regions joined by the flexiblelinker [see e.g. Bird et al. (1988) Science 242:423-426; Huston et al.(1988) Proc. Natl. Acad. Sci. USA 85:5879-5883; McCafferty et al.,(1990) Nature 348:552-554].

Production of Monoclonal Antibodies

According to the invention the BST1 or a fragment or derivative thereofmay be used as an immunogen to generate antibodies whichimmunospecifically bind such an immunogen. Such immunogens can beisolated by any convenient means. One skilled in the art will recognizethat many procedures are available for the production of antibodies, forexample, as described in Antibodies, A Laboratory Manual, Ed Harlow andDavid Lane, Cold Spring Harbor Laboratory (1988), Cold Spring Harbor,N.Y. One skilled in the art will also appreciate that binding fragmentsor Fab fragments which mimic antibodies can also be prepared fromgenetic information by various procedures [Antibody Engineering: APractical Approach (Borrebaeck, C., ed.), 1995, Oxford University Press,Oxford; J. Immunol. 149, 3914-3920 (1992)].

In one embodiment of the invention, antibodies to a specific domain ofthe BST1 are produced. In a specific embodiment, hydrophilic fragmentsof the BST1 are used as immunogens for antibody production.

In the production of antibodies, screening for the desired antibody canbe accomplished by techniques known in the art, e.g. ELISA(enzyme-linked immunosorbent assay). For example, to select antibodieswhich recognize a specific domain of the BST1, one may assay generatedhybridomas for a product which binds to an BST1 fragment containing sucha domain. For selection of an antibody that specifically binds a firstBST1 homolog but which does not specifically bind to (or binds lessavidly to) a second BST1 homolog, one can select on the basis ofpositive binding to the first BST1 homolog and a lack of binding to (orreduced binding to) the second BST1 homolog. Similarly, for selection ofan antibody that specifically binds the BST1 but which does notspecifically bind to (or binds less avidly to) a different isoform ofthe same protein (such as a different glycoform having the same corepeptide as the BST1), one can select on the basis of positive binding tothe BST1 and a lack of binding to (or reduced binding to) the differentisoform (e.g. a different glycoform). Thus, the present inventionprovides an antibody (such as a monoclonal antibody) that binds withgreater affinity (for example at least 2-fold, such as at least 5-fold,particularly at least 10-fold greater affinity) to the BST1 than to adifferent isoform or isoforms (e.g. glycoforms) of the BST1.

Polyclonal antibodies which may be used in the methods of the inventionare heterogeneous populations of antibody molecules derived from thesera of immunized animals. Unfractionated immune serum can also be used.Various procedures known in the art may be used for the production ofpolyclonal antibodies to the BST1, a fragment of the BST1, anBST1-related polypeptide, or a fragment of an BST1-related polypeptide.For example, one way is to purify polypeptides of interest or tosynthesize the polypeptides of interest using, e.g. solid phase peptidesynthesis methods well known in the art. See, e.g. Guide to ProteinPurification, Murray P. Deutcher, ed., Meth. Enzymol. Vol 182 (1990);Solid Phase Peptide Synthesis, Greg B. Fields ed., Meth. Enzymol. Vol289 (1997); Kiso et al., Chem. Pharm. Bull. (Tokyo) 38: 1192-99, 1990;Mostafavi et al., Biomed. Pept. Proteins Nucleic Acids 1: 255-60, 1995;Fujiwara et al., Chem. Pharm. Bull. (Tokyo) 44: 1326-31, 1996. Theselected polypeptides may then be used to immunize by injection varioushost animals, including but not limited to rabbits, mice, rats, etc., togenerate polyclonal or monoclonal antibodies. Various adjuvants (i.e.immunostimulants) may be used to enhance the immunological response,depending on the host species, including, but not limited to, completeor incomplete Freund's adjuvant, a mineral gel such as aluminumhydroxide, surface active substance such as lysolecithin, pluronicpolyol, a polyanion, a peptide, an oil emulsion, keyhole limpethemocyanin, dinitrophenol, and an adjuvant such as BCG (bacilleCalmette-Guerin) or corynebacterium parvum. Additional adjuvants arealso well known in the art.

For preparation of monoclonal antibodies (mAbs) directed toward theBST1, any technique which provides for the production of antibodymolecules by continuous cell lines in culture may be used. For example,the hybridoma technique originally developed by Kohler and Milstein(1975, Nature 256:495-497), as well as the trioma technique, the humanB-cell hybridoma technique [Kozbor et al. (1983) Immunology Today 4:72],and the EBV-hybridoma technique to produce human monoclonal antibodies[Cole et al. (1985) in Monoclonal Antibodies and Cancer Therapy, Alan R.Liss, Inc., pp. 77-96]. Such antibodies may be of any immunoglobulinclass including IgG, IgM, IgE, IgA, IgD and any subclass thereof. Thehybridoma producing the monoclonal antibodies may be cultivated in vitroor in vivo. In an additional embodiment of the invention, monoclonalantibodies can be produced in germ-free animals utilizing knowntechnology (PCT/US90/02545, incorporated herein by reference).

The preferred animal system for preparing hybridomas is the murinesystem. Hybridoma production in the mouse is a very well-establishedprocedure. Immunization protocols and techniques for isolation ofimmunized splenocytes for fusion are known in the art. Fusion partners(e.g. murine myeloma cells) and fusion procedures are also known.

The monoclonal antibodies include but are not limited to humanmonoclonal antibodies and chimeric monoclonal antibodies (e.g.human-mouse chimeras).

Chimeric or humanized antibodies of the present invention can beprepared based on the sequence of a non-human monoclonal antibodyprepared as described above. DNA encoding the heavy and light chainimmunoglobulins can be obtained from the non-human hybridoma of interestand engineered to contain non-murine (e.g. human) immunoglobulinsequences using standard molecular biology techniques. For example, tocreate a chimeric antibody, murine variable regions can be linked tohuman constant regions using methods known in the art (see e.g. U.S.Pat. No. 4,816,567 to Cabilly et al.). To create a humanized antibody,murine CDR regions can be inserted into a human framework using methodsknown in the art (see e.g. U.S. Pat. No. 5,225,539 to Winter, and U.S.Pat. Nos. 5,530,101; 5,585,089; 5,693,762 and 6,180,370 to Queen etal.).

Completely human antibodies can be produced using transgenic ortranschromosomic mice which are incapable of expressing endogenousimmunoglobulin heavy and light chain genes, but which can express humanheavy and light chain genes. The transgenic mice are immunized in thenormal fashion with a selected antigen, e.g. all or a portion of theBST1. Monoclonal antibodies directed against the antigen can be obtainedusing conventional hybridoma technology. The human immunoglobulintransgenes harbored by the transgenic mice rearrange during B celldifferentiation, and subsequently undergo class switching and somaticmutation. Thus, using such a technique, it is possible to producetherapeutically useful IgG, IgA, IgM and IgE antibodies. Thesetransgenic and transchromosomic mice include mice of the HuMAb Mouse®(Medarex®, Inc.) and KM Mouse® strains. The HuMAb Mouse® strain(Medarex®, Inc.) is described in Lonberg and Huszar (1995, Int. Rev.Immunol. 13:65-93). For a detailed discussion of this technology forproducing human antibodies and human monoclonal antibodies and protocolsfor producing such antibodies, see, e.g. U.S. Pat. No. 5,625,126; U.S.Pat. No. 5,633,425; U.S. Pat. No. 5,569,825; U.S. Pat. No. 5,661,016;and U.S. Pat. No. 5,545,806. The KM Mouse® strain refers to a mouse thatcarries a human heavy chain transgene and a human light chaintranschromosome and is described in detail in PCT Publication WO02/43478 to Ishida et al.

Still further, alternative transgenic animal systems expressing humanimmunoglobulin genes are available in the art and can be used to raiseanti-BST1 antibodies of the invention. For example, an alternativetransgenic system referred to as the Xenomouse (Amgen, Inc.) can beused; such mice are described in, for example, U.S. Pat. Nos. 5,939,598;6,075,181; 6,114,598; 6,150,584 and 6,162,963 to Kucherlapati et al.

Completely human antibodies which recognize a selected epitope can begenerated using a technique referred to as “guided selection”. In thisapproach a selected non-human monoclonal antibody, e.g. a mouseantibody, is used to guide the selection of a completely human antibodyrecognizing the same epitope [Jespers et al. (1994) Biotechnology12:899-903].

Moreover, alternative transchromosomic animal systems expressing humanimmunoglobulin genes are available in the art and can be used to raiseanti-BST1 antibodies. For example, mice carrying both a human heavychain transchromosome and a human light chain tranchromosome, referredto as “TC mice” can be used; such mice are described in Tomizuka et al.(2000) Proc. Natl. Acad. Sci. USA 97:722-727. Furthermore, cows carryinghuman heavy and light chain transchromosomes have been described in theart [Kuroiwa et al. (2002) Nature Biotechnology 20:889-894] and PCTpublication No. WO2002/092812 and can be used to raise anti-BST1antibodies.

Human monoclonal antibodies of the invention can also be prepared usingSCID mice into which human immune cells have been reconstituted suchthat a human antibody response can be generated upon immunization. Suchmice are described in, for example, U.S. Pat. Nos. 5,476,994 and3,698,767.

The antibodies of the present invention can be generated by the use ofphage display technology to produce and screen libraries of polypeptidesfor binding to a selected target [see, e.g. Cwirla et al., Proc. Natl.Acad. Sci. USA 87, 6378-82, 1990; Devlin et al., Science 249, 404-6,1990, Scott and Smith, Science 249, 386-88, 1990; and Ladner et al.,U.S. Pat. No. 5,571,698]. A basic concept of phage display methods isthe establishment of a physical association between DNA encoding apolypeptide to be screened and the polypeptide. This physicalassociation is provided by the phage particle, which displays apolypeptide as part of a capsid enclosing the phage genome which encodesthe polypeptide. The establishment of a physical association betweenpolypeptides and their genetic material allows simultaneous massscreening of very large numbers of phage bearing different polypeptides.Phage displaying a polypeptide with affinity to a target bind to thetarget and these phage are enriched by affinity screening to the target.The identity of polypeptides displayed from these phages can bedetermined from their respective genomes. Using these methods apolypeptide identified as having a binding affinity for a desired targetcan then be synthesized in bulk by conventional means. See, e.g. U.S.Pat. No. 6,057,098, which is hereby incorporated in its entirety,including all tables, figures, and claims. In particular, such phage canbe utilized to display antigen binding domains expressed from arepertoire or combinatorial antibody library (e.g. human or murine).Phage expressing an antigen binding domain that binds the antigen ofinterest can be selected or identified with antigen, e.g. using labeledantigen or antigen bound or captured to a solid surface or bead. Phageused in these methods are typically filamentous phage including fd andM13 binding domains expressed from phage with Fab, Fv or disulfidestabilized Fv antibody domains recombinantly fused to either the phagegene III or gene VIII protein. Phage display methods that can be used tomake the antibodies of the present invention include those disclosed inBrinkman et al. (1995) J. Immunol. Methods 182:41-50; Ames et al. (1995)J. Immunol. Methods 184:177-186; Kettleborough et al., Eur. J. Immunol.24:952-958 (1994); Persic et al. (1997) Gene 187 9-18; Burton et al.(1994) Advances in Immunology 57:191-280; PCT Application No.PCT/GB91/01134; PCT Publications WO 90/02809; WO 91/10737; WO 92/01047;WO 92/18619; WO 93/11236; WO 95/15982; WO 95/20401; and U.S. Pat. Nos.5,698,426; 5,223,409; 5,403,484; 5,580,717; 5,427,908; 5,750,753;5,821,047; 5,571,698; 5,427,908; 5,516,637; 5,780,225; 5,658,727;5,733,743 and 5,969,108; each of which is incorporated herein byreference in its entirety.

As described in the above references, after phage selection, theantibody coding regions from the phage can be isolated and used togenerate whole antibodies, including human antibodies, or any otherdesired antigen binding fragment, and expressed in any desired host,including mammalian cells, insect cells, plant cells, yeast, andbacteria, e.g. as described in detail below. For example, techniques torecombinantly produce Fab, Fab′ and F(ab′)₂ fragments can also beemployed using methods known in the art such as those disclosed in PCTpublication WO 92/22324; Mullinax et al. (1992) BioTechniques12(6):864-869; and Sawai et al. (1995) AJRI 34:26-34; and Better et al.(1988) Science 240:1041-1043 (said references incorporated by referencein their entireties).

Examples of techniques which can be used to produce single-chain Fvs andantibodies include those described in U.S. Pat. Nos. 4,946,778 and5,258,498; Huston et al. (1991), Methods in Enzymology 203:46-88; Shu etal. (1993) PNAS 90:7995-7999; and Skerra et al. (1988) Science240:1038-1040.

The invention provides functionally active fragments, derivatives oranalogs of the anti-BST1 immunoglobulin molecules. Functionally activemeans that the fragment, derivative or analog is able to elicitanti-anti-idiotype antibodies (i.e. tertiary antibodies) that recognizethe same antigen that is recognized by the antibody from which thefragment, derivative or analog is derived. Specifically, in a particularembodiment the antigenicity of the idiotype of the immunoglobulinmolecule may be enhanced by deletion of framework and CDR sequences thatare C-terminal to the CDR sequence that specifically recognizes theantigen. To determine which CDR sequences bind the antigen, syntheticpeptides containing the CDR sequences can be used in binding assays withthe antigen by any binding assay method known in the art.

The present invention provides antibody fragments such as, but notlimited to, F(ab′)₂ fragments and Fab fragments. Antibody fragmentswhich recognize specific epitopes may be generated by known techniques.F(ab′)₂ fragments consist of the variable region, the light chainconstant region and the C_(H)1 domain of the heavy chain and aregenerated by pepsin digestion of the antibody molecule. Fab fragmentsare generated by reducing the disulfide bridges of the F(ab′)₂fragments. The invention also provides heavy chain and light chaindimers of the antibodies of the invention, or any minimal fragmentthereof such as Fvs or single chain antibodies (SCAs) [e.g. as describedin U.S. Pat. No. 4,946,778; Bird, (1988) Science 242:423-42; Huston etal. (1988) Proc. Natl. Acad. Sci. USA 85:5879-5883; and Ward et al.(1989) Nature 334:544-5], or any other molecule with the samespecificity as the antibody of the invention. Single chain antibodiesare formed by linking the heavy and light chain fragments of the Fvregion via an amino acid bridge, resulting in a single chainpolypeptide. Techniques for the assembly of functional Fv fragments inE. coli may be used [Skerra et al. (1988) Science 242:1038-1041].

In other embodiments, the invention provides fusion proteins of theimmunoglobulins of the invention (or functionally active fragmentsthereof), for example in which the immunoglobulin is fused via acovalent bond (e.g. a peptide bond), at either the N-terminus or theC-terminus to an amino acid sequence of another protein (or portionthereof, preferably at least 10, 20 or 50 amino acid portion of theprotein) that is not the immunoglobulin. Preferably the immunoglobulin,or fragment thereof, is covalently linked to the other protein at theN-terminus of the constant domain. As stated above, such fusion proteinsmay facilitate purification, increase half-life in vivo, and enhance thedelivery of an antigen across an epithelial barrier to the immunesystem.

The immunoglobulins of the invention include analogs and derivativesthat are modified, i.e. by the covalent attachment of any type ofmolecule as long as such covalent attachment does not impairimmunospecific binding. For example, but not by way of limitation, thederivatives and analogs of the immunoglobulins include those that havebeen further modified, e.g. by glycosylation, acetylation, pegylation,phosphylation, amidation, derivatization by known protecting/blockinggroups, proteolytic cleavage, linkage to a cellular ligand or otherprotein, etc. Any of numerous chemical modifications may be carried outby known techniques, including, but not limited to specific chemicalcleavage, acetylation, formylation, etc. Additionally, the analog orderivative may contain one or more non-classical amino acids.

Immunization of Mice

Mice can be immunized with a purified or enriched preparation of theBST1 antigen and/or recombinant BST1, or cells expressing BST1.Preferably, the mice will be 6-16 weeks of age upon the first infusion.For example, a purified or recombinant preparation (100 μg) of the BST1antigen can be used to immunize the mice intraperitoneally.

Cumulative experience with various antigens has shown that the micerespond when immunized intraperitoneally (IP) with antigen in completeFreund's adjuvant. However, adjuvants other than Freund's are also foundto be effective. In addition, whole cells in the absence of adjuvant arefound to be highly immunogenic. The immune response can be monitoredover the course of the immunization protocol with plasma samples beingobtained by retroorbital bleeds. The plasma can be screened by ELISA (asdescribed below) to test for satisfactory titres. Mice can be boostedintravenously with antigen on 3 consecutive days with sacrifice andremoval of the spleen taking place 5 days later. In one embodiment, A/Jmouse strains (Jackson Laboratories, Bar Harbor, Me.) may be used.

Generation of Transfectomas Producing Monoclonal Antibodies

Antibodies of the invention can be produced in a host cell transfectomausing, for example, a combination of recombinant DNA techniques and genetransfection methods as is well known in the art [e.g. Morrison, S.(1985) Science 229:1202].

For example, to express the antibodies, or antibody fragments thereof,DNAs encoding partial or full-length light and heavy chains, can beobtained by standard molecular biology techniques (e.g. PCRamplification or cDNA cloning using a hybridoma that expresses theantibody of interest) and the DNAs can be inserted into expressionvectors such that the genes are operatively linked to transcriptionaland translational control sequences. In this context, the term“operatively linked” is intended to mean that an antibody gene isligated into a vector such that transcriptional and translationalcontrol sequences within the vector serve their intended function ofregulating the transcription and translation of the antibody gene. Theexpression vector and expression control sequences are chosen to becompatible with the expression host cell used.

The host cell may be co-transfected with two expression vectors of theinvention, the first vector encoding a heavy chain derived polypeptideand the second vector encoding a light chain derived polypeptide. Thetwo vectors may contain identical selectable markers which enable equalexpression of heavy and light chain polypeptides. Alternatively, asingle vector may be used which encodes both heavy and light chainpolypeptides. In such situations, the light chain should be placedbefore the heavy chain to avoid an excess of toxic free heavy chain[Proudfoot (1986) Nature 322:52; Kohler (1980) Proc. Natl. Acad. Sci.USA 77:2197]. The coding sequences for the heavy and light chains maycomprise cDNA or genomic DNA.

The antibody genes are inserted into the expression vector by standardmethods (e.g. ligation of complementary restriction sites on theantibody gene fragment and vector, or blunt end ligation if norestriction sites are present). The light and heavy chain variableregions of the antibodies described herein can be used to createfull-length antibody genes of any antibody isotype by inserting theminto expression vectors already encoding heavy chain constant and lightchain constant regions of the desired isotype such that the V_(H)segment is operatively linked to the C_(H) segment(s) within the vectorand the V_(K) segment is operatively linked to the C_(L) segment withinthe vector. Additionally or alternatively, the recombinant expressionvector can encode a signal peptide that facilitates secretion of theantibody chain from a host cell. The antibody chain gene can be clonedinto the vector such that the signal peptide is linked in-frame to theamino terminus of the antibody chain gene. The signal peptide can be animmunoglobulin signal peptide or a heterologous signal peptide (i.e. asignal peptide from a non-immunoglobulin protein).

In addition to the antibody chain genes, the recombinant expressionvectors of the invention carry regulatory sequences that control theexpression of the antibody chain genes in a host cell. The term“regulatory sequence” is intended to include promoters, enhancers andother expression control elements (e.g. polyadenylation signals) thatcontrol the transcription or translation of the antibody chain genes.Such regulatory sequences are described, for example, in Goeddel (GeneExpression Technology, Methods in Enzymology 185, Academic Press, SanDiego, Calif. (1990). It will be appreciated by those skilled in the artthat the design of the expression vector, including the selection ofregulatory sequences, may depend on such factors as the choice of thehost cell to be transformed, the level of expression of protein desired,etc. Preferred regulatory sequences for mammalian host cell expressioninclude viral elements that direct high levels of protein expression inmammalian cells, such as promoters and/or enhancers derived fromcytomegalovirus (CMV), Simian Virus 40 (SV40), adenovirus, (e.g. theadenovirus major late promoter (AdMLP) and polyoma. Alternatively,nonviral regulatory sequences may be used, such as the ubiquitinpromoter or β-globin promoter. Still further, regulatory elementscomposed of sequences from different sources, such as the SRα promotersystem, which contains sequences from the SV40 early promoter and thelong terminal repeat of human T cell leukemia virus type 1 [Takebe, Y.et al. (1988) Mol. Cell. Biol. 8:466-472].

In addition to the antibody chain genes and regulatory sequences, therecombinant expression vectors of the invention may carry additionalsequences, such as sequences that regulate replication of the vector inhost cells (e.g. origins of replication) and selectable marker genes.The selectable marker gene facilitates selection of host cells intowhich the vector has been introduced (see, e.g. U.S. Pat. Nos.4,399,216, 4,634,665 and 5,179,017, all by Axel et al.). For example,typically the selectable marker gene confers resistance to drugs, suchas G418, hygromycin or methotrexate, on a host cell into which thevector has been introduced. Preferred selectable marker genes includethe dihydrofolate reductase (DHFR) gene (for use in dhfr-host cells withmethotrexate selection/amplification) and the neo gene (for G418selection).

For expression of the light and heavy chains, the expression vector(s)encoding the heavy and light chains is transfected into a host cell bystandard techniques. The various forms of the term “transfection” areintended to encompass a wide variety of techniques commonly used for theintroduction of exogenous DNA into a prokaryotic or eukaryotic hostcell, e.g. electroporation, calcium-phosphate precipitation,DEAE-dextran transfection and the like. Although it is theoreticallypossible to express the antibodies of the invention in eitherprokaryotic or eukaryotic host cells, expression of antibodies ineukaryotic cells, and most preferably mammalian host cells, is the mostpreferred because such eukaryotic cells, and in particular mammaliancells, are more likely than prokaryotic cells to assemble and secrete aproperly folded and immunologically active antibody. Prokaryoticexpression of antibody genes has been reported to be ineffective forproduction of high yields of active antibody [Boss, M. A. and Wood, C.R. (1985) Immunology Today 6:12-13].

Preferred mammalian host cells for expressing the recombinant antibodiesof the invention include Chinese hamster ovary cells (CHO), inconjunction with a vector such as the major intermediate early genepromoter element from human cytomegalovirus [Foecking et al., 1986, Gene45:101; Cockett et al. (1990) BioTechnology 8:2], dhfr-CHO cells,described in Urlaub and Chasin (1980) Proc. Natl. Acad. Sci. USA77:4216-4220, used with a DHFR selectable marker, e.g. as described inR. J. Kaufman and P. A. Sharp (1982) J. Mol. Biol. 159:601-621), NSOmyeloma cells, COS cells and SP2 cells. In particular, for use with NSOmyeloma cells, another preferred expression system is the GS geneexpression system disclosed in WO 87/04462 (to Wilson), WO 89/01036 (toBebbington) and EP 338,841 (to Bebbington).

A variety of host expression vector systems may be utilized to expressan antibody molecule of the invention. Such host-expression systemsrepresent vehicles by which the coding sequences of interest may beproduced and subsequently purified, but also represent cells which may,when transformed or transfected with the appropriate nucleotide codingsequences, express the antibody molecule of the invention in situ. Theseinclude but are not limited to microorganisms such as bacteria (e.g. E.coli, B. subtilis) transformed with recombinant bacteriophage DNA,plasmid DNA or cosmid DNA expression vectors containing antibody codingsequences; yeast (e.g. Saccharomyces, Pichia) transformed withrecombinant yeast expression vectors containing antibody codingsequences; insect cell systems infected with recombinant virusexpression vectors (e.g. baculovirus) containing the antibody codingsequences; plant cell systems infected with recombinant virus expressionvectors (e.g. cauliflower mosaic virus, CaMV; tobacco mosaic virus, TMV)or transformed with recombinant plasmid expression vectors (e.g. Tiplasmid) containing antibody coding sequences; or mammalian cell systems(e.g. COS, CHO, BHK, 293, 3T3 cells) harboring recombinant expressionconstructs containing promoters derived from the genome of mammaliancells (e.g. metallothionein promoter) or from mammalian viruses (e.g.the adenovirus late promoter; the vaccinia virus 7.5K promoter).

In bacterial systems, a number of expression vectors may beadvantageously selected depending upon the use intended for the antibodymolecule being expressed. For example, when a large quantity of such aprotein is to be produced, for the generation of pharmaceuticalcompositions comprising an antibody molecule, vectors which direct theexpression of high levels of fusion protein products that are readilypurified may be desirable. Such vectors include, but are not limited, tothe E. coli expression vector pUR278 (Ruther et al. (1983) EMBO J.2:1791), in which the antibody coding sequence may be ligatedindividually into the vector in frame with the lac Z coding region sothat a fusion protein is produced; pIN vectors [Inouye & Inouye (1985)Nucleic Acids Res. 13:3101-3109; Van Heeke & Schuster (1989) J. Biol.Chem. 24:5503-5509]; and the similar pGEX vectors may also be used toexpress foreign polypeptides as fusion proteins with glutathioneS-transferase (GST). In general, such fusion proteins are soluble andcan easily be purified from lysed cells by adsorption and binding to amatrix glutathione-agarose beads followed by elution in the presence offree glutathione. The pGEX vectors are designed to include thrombin orfactor Xa protease cleavage sites so that the cloned target gene productcan be released from the GST moiety.

In an insect system, Autographa californica nuclear polyhedrosis virus(AcNPV) is used as a vector to express foreign genes. The virus grows inSpodoptera frugiperda cells. The antibody coding sequence may be clonedindividually into non-essential regions (for example the polyhedringene) of the virus and placed under control of an AcNPV promoter (forexample the polyhedrin promoter). In mammalian host cells, a number ofviral-based expression systems (e.g. an adenovirus expression system)may be utilized.

As discussed above, a host cell strain may be chosen which modulates theexpression of the inserted sequences, or modifies and processes the geneproduct in the specific fashion desired. Such modifications (e.g.glycosylation) and processing (e.g. cleavage) of protein products may beimportant for the function of the protein.

For long-term, high-yield production of recombinant antibodies, stableexpression is preferred. For example, cell lines that stably express anantibody of interest can be produced by transfecting the cells with anexpression vector comprising the nucleotide sequence of the antibody andthe nucleotide sequence of a selectable (e.g. neomycin or hygromycin),and selecting for expression of the selectable marker. Such engineeredcell lines may be particularly useful in screening and evaluation ofcompounds that interact directly or indirectly with the antibodymolecule.

The expression levels of the antibody molecule can be increased byvector amplification [for a review, see Bebbington and Hentschel, Theuse of vectors based on gene amplification for the expression of clonedgenes in mammalian cells in DNA cloning, Vol. 3. (Academic Press, NewYork, 1987)]. When a marker in the vector system expressing antibody isamplifiable, increase in the level of inhibitor present in culture ofhost cell will increase the number of copies of the marker gene. Sincethe amplified region is associated with the antibody gene, production ofthe antibody will also increase [Crouse et al., 1983, Mol. Cell. Biol.3:257].

When recombinant expression vectors encoding antibody genes areintroduced into mammalian host cells, the antibodies are produced byculturing the host cells for a period of time sufficient to allow forexpression of the antibody in the host cells or, more preferably,secretion of the antibody into the culture medium in which the hostcells are grown. Once the antibody molecule of the invention has beenrecombinantly expressed, it may be purified by any method known in theart for purification of an antibody molecule, for example, bychromatography (e.g. ion exchange chromatography, affinitychromatography such as with protein A or specific antigen, and sizingcolumn chromatography), centrifugation, differential solubility, or byany other standard technique for the purification of proteins.

Alternatively, any fusion protein may be readily purified by utilizingan antibody specific for the fusion protein being expressed. Forexample, a system described by Janknecht et al. allows for the readypurification of non-denatured fusion proteins expressed in human celllines [Janknecht et al., 1991, Proc. Natl. Acad. Sci. USA 88:8972-897].In this system, the gene of interest is subcloned into a vacciniarecombination plasmid such that the open reading frame of the gene istranslationally fused to an amino-terminal tag consisting of sixhistidine residues. The tag serves as a matrix binding domain for thefusion protein. Extracts from cells infected with recombinant vacciniavirus are loaded onto Ni²⁺ nitriloacetic acid-agarose columns andhistidine-tagged proteins are selectively eluted withimidazole-containing buffers.

Characterization of Antibody Binding to Antigen

The antibodies that are generated by these methods may then be selectedby first screening for affinity and specificity with the purifiedpolypeptide of interest and, if required, comparing the results to theaffinity and specificity of the antibodies with polypeptides that aredesired to be excluded from binding. The antibodies can be tested forbinding to the BST1 by, for example, standard ELISA. The screeningprocedure can involve immobilization of the purified polypeptides inseparate wells of microtiter plates. The solution containing a potentialantibody or groups of antibodies is then placed into the respectivemicrotiter wells and incubated for about 30 min to 2 h. The microtiterwells are then washed and a labeled secondary antibody (for example, ananti-mouse antibody conjugated to alkaline phosphatase if the raisedantibodies are mouse antibodies) is added to the wells and incubated forabout 30 min and then washed. Substrate is added to the wells and acolor reaction will appear where antibody to the immobilizedpolypeptide(s) is present.

The antibodies so identified may then be further analyzed for affinityand specificity in the assay design selected. In the development ofimmunoassays for a target protein, the purified target protein acts as astandard with which to judge the sensitivity and specificity of theimmunoassay using the antibodies that have been selected. Because thebinding affinity of various antibodies may differ, certain antibodypairs (e.g. in sandwich assays) may interfere with one anothersterically, etc., assay performance of an antibody may be a moreimportant measure than absolute affinity and specificity of an antibody.

Those skilled in the art will recognize that many approaches can betaken in producing antibodies or binding fragments and screening andselecting for affinity and specificity for the various polypeptides, butthese approaches do not change the scope of the invention.

To determine if the selected anti-BST1 monoclonal antibodies bind tounique epitopes, each antibody can be biotinylated using commerciallyavailable reagents (Pierce, Rockford, Ill.). Competition studies usingunlabeled monoclonal antibodies and biotinylated monoclonal antibodiescan be performed using the BST1 coated-ELISA plates. Biotinylated mAbbinding can be detected with a streptavidin-alkaline phosphatase probe.

To determine the isotype of purified antibodies, isotype ELISAs can beperformed using reagents specific for antibodies of a particularisotype.

Anti-BST1 antibodies can be further tested for reactivity with the BST1antigen by Western blotting. Briefly, BST1 can be prepared and subjectedto sodium dodecyl sulfate polyacrylamide gel electrophoresis. Afterelectrophoresis, the separated antigens are transferred tonitrocellulose membranes, blocked with 10% fetal calf serum, and probedwith the monoclonal antibodies to be tested.

The binding specificity of an antibody of the invention may also bedetermined by monitoring binding of the antibody to cells expressingBST1, for example, by flow cytometry. Typically, a cell line, such as aCHO cell line, may be transfected with an expression vector encodingBST1. The transfected protein may comprise a tag, such as a myc-tag,preferably at the N-terminus, for detection using an antibody to thetag. Binding of an antibody of the invention to BST1 may be determinedby incubating the transfected cells with the antibody, and detectingbound antibody. Binding of an antibody to the tag on the transfectedprotein may be used as a positive control.

The specificity of an antibody of the invention for BST1 may be furtherstudied by determining whether or not the antibody binds to otherproteins, such as another member of the Eph family using the samemethods by which binding to BST1 is determined.

Immunoconjugates

In another aspect, the present invention features an anti-BST1 antibody,or a fragment thereof, conjugated to a therapeutic moiety, such as acytotoxin, a drug (e.g. an immunosuppressant) or a radiotoxin. Suchconjugates are referred to herein as “immunoconjugates”.Immunoconjugates that include one or more cytotoxins are referred to as“immunotoxins”. A cytotoxin or cytotoxic agent includes any agent thatis detrimental to (e.g. kills) cells. Examples include taxol,cytochalasin B, gramicidin D, ethidium bromide, emetine, mitomycin,etoposide, tenoposide, vincristine, vinblastine, colchicin, doxorubicin,daunorubicin, dihydroxy anthracin dione, mitoxantrone, mithramycin,actinomycin D, 1-dehydrotestosterone, glucocorticoids, procaine,tetracaine, lidocaine, propranolol, and puromycin and analogs orhomologs thereof. Therapeutic agents also include, for example,antimetabolites (e.g. methotrexate, 6-mercaptopurine, 6-thioguanine,cytarabine, 5-fluorouracil decarbazine), alkylating agents (e.g.mechlorethamine, thioepa chlorambucil, melphalan, carmustine (BSNU) andlomustine (CCNU), cyclothosphamide, busulfan, dibromomannitol,streptozotocin, mitomycin C, and cis-dichlorodiamine platinum (II) (DDP)cisplatin), anthracyclines (e.g. daunorubicin (formerly daunomycin) anddoxorubicin), antibiotics (e.g. dactinomycin (formerly actinomycin),bleomycin, mithramycin, and anthramycin (AMC)), and anti-mitotic agents(e.g. vincristine and vinblastine).

Other preferred examples of therapeutic cytotoxins that can beconjugated to an antibody of the invention include duocarmycins,calicheamicins, maytansines and auristatins, and derivatives thereof. Anexample of a calicheamicin antibody conjugate is commercially available(Mylotarg®; American Home Products).

Cytotoxins can be conjugated to antibodies of the invention using linkertechnology available in the art. Examples of linker types that have beenused to conjugate a cytotoxin to an antibody include, but are notlimited to, hydrazones, thioethers, esters, disulfides andpeptide-containing linkers. A linker can be chosen that is, for example,susceptible to cleavage by low pH within the lysosomal compartment orsusceptible to cleavage by proteases, such as proteases preferentiallyexpressed in tumor tissue such as cathepsins (e.g. cathepsins B, C, D).

Examples of cytotoxins are described, for example, in U.S. Pat. Nos.6,989,452, 7,087,600, and 7,129,261, and in PCT Application Nos.PCT/US2002/17210, PCT/US2005/017804, PCT/US2006/37793,PCT/US2006/060050, PCT/US2006/060711, WO2006/110476, and in U.S. PatentApplication No. 60/891,028, all of which are incorporated herein byreference in their entirety. For further discussion of types ofcytotoxins, linkers and methods for conjugating therapeutic agents toantibodies, see also Saito, G. et al. (2003) Adv. Drug Deliv. Rev.55:199-215; Trail, P. A. et al. (2003) Cancer Immunol. Immunother.52:328-337; Payne, G. (2003) Cancer Cell 3:207-212; Allen, T. M. (2002)Nat. Rev. Cancer 2:750-763; Pastan, I. and Kreitman, R. J. (2002) Curr.Opin. Investig. Drugs 3:1089-1091; Senter, P. D. and Springer, C. J.(2001) Adv. Drug Deliv. Rev. 53:247-264.

Antibodies of the present invention also can be conjugated to aradioactive isotope to generate cytotoxic radiopharmaceuticals, alsoreferred to as radioimmunoconjugates. Examples of radioactive isotopesthat can be conjugated to antibodies for use diagnostically ortherapeutically include, but are not limited to, iodine-131, indium111,yttrium90 and lutetium177. Method for preparing radioimmunoconjugatesare established in the art. Examples of radioimmunoconjugates arecommercially available, including Zevalin® (IDEC Pharmaceuticals) andBexxar® (Corixa Pharmaceuticals), and similar methods can be used toprepare radioimmunoconjugates using the antibodies of the invention.

The antibody conjugates of the invention can be used to modify a givenbiological response, and the drug moiety is not to be construed aslimited to classical chemical therapeutic agents. For example, the drugmoiety may be a protein or polypeptide possessing a desired biologicalactivity. Such proteins may include, for example, an enzymaticallyactive toxin, or active fragment thereof, such as abrin, ricin A,pseudomonas exotoxin, or diphtheria toxin; a protein such as tumornecrosis factor or interferon-γ; or, biological response modifiers suchas, for example, lymphokines, interleukin-1 (“IL-1”), interleukin-2(“IL-2”), interleukin-6 (“IL-6”), granulocyte macrophage colonystimulating factor (“GM-CSF”), granulocyte colony stimulating factor(“G-CSF”), or other growth factors.

Techniques for conjugating such therapeutic moiety to antibodies arewell known, see, e.g. Amon et al., “Monoclonal Antibodies ForImmunotargeting Of Drugs In Cancer Therapy,” in Monoclonal AntibodiesAnd Cancer Therapy, Reisfeld et al. (eds.), pp. 243-56 (Alan R. Liss,Inc. 1985); Hellstrom et al., “Antibodies For Drug Delivery,” inControlled Drug Delivery (2nd Ed.), Robinson et al. (eds.), pp. 623-53(Marcel Dekker, Inc. 1987); Thorpe, “Antibody Carriers Of CytotoxicAgents In Cancer Therapy: A Review,” in Monoclonal Antibodies '84:Biological And Clinical Applications, Pinchera et al. (eds.), pp.475-506 (1985); “Analysis, Results, And Future Prospective Of TheTherapeutic Use Of Radiolabeled Antibody In Cancer Therapy,” inMonoclonal Antibodies For Cancer Detection And Therapy, Baldwin et al.(eds.), pp. 303-16 (Academic Press 1985), and Thorpe et al., Immunol.Rev., 62:119-58 (1982).

Bispecific Molecules

In another aspect, the present invention features bispecific moleculescomprising an anti-BST1 antibody, or a fragment thereof, of theinvention. An antibody of the invention, or antigen-binding portionsthereof, can be derivatized or linked to another functional molecule,e.g. another peptide or protein (e.g. another antibody or ligand for areceptor) to generate a bispecific molecule that binds to at least twodifferent binding sites or target molecules. The antibody of theinvention may in fact be derivatized or linked to more than one otherfunctional molecule to generate multispecific molecules that bind tomore than two different binding sites and/or target molecules; suchmultispecific molecules are also intended to be encompassed by the term“bispecific molecule” as used herein. To create a bispecific molecule ofthe invention, an antibody of the invention can be functionally linked(e.g. by chemical coupling, genetic fusion, noncovalent association orotherwise) to one or more other binding molecules, such as anotherantibody, antibody fragment, peptide or binding mimetic, such that abispecific molecule results.

Accordingly, the present invention includes bispecific moleculescomprising at least one first binding specificity for a first targetepitope (i.e. BST1) and a second binding specificity for a second targetepitope. The second target epitope maybe present on the same targetprotein as that bound by the first binding specificity; or the secondtarget epitope may be present of a different target protein to thatbound by the first protein to that bound by the first bindingspecificity. The second target epitope may be present on the same cellas the first target epitope (i.e. BST1); or the second target epitopemay be present on a target which is not displayed by the cell whichdisplays the first target epitope. As used herein, the term ‘bindingspecificity’ refers to a moiety comprising at least one antibodyvariable domain.

In a one embodiment of the invention, the second target epitope is an Fcreceptor, e.g. human FcγRI (CD64) or a human Fcα receptor (CD89).Therefore, the invention includes bispecific molecules capable ofbinding both to FcγR or FcαR expressing effector cells (e.g. monocytes,macrophages or polymorphonuclear cells (PMNs), and to target cellsexpressing BST1. These bispecific molecules target BST1 expressing cellsto effector cell and trigger Fc receptor-mediated effector cellactivities, such as phagocytosis of BST1 expressing cells, antibodydependent cell-mediated cytotoxicity (ADCC), cytokine release, orgeneration of superoxide anion.

In another embodiment of the invention, the second target epitope is CD3or CD5. Therefore, the invention includes bispecific molecules capableof binding both to CD3 or CD5 expressing effector cells (e.g. CD3 or CD5expressing cytotoxic T cells), and to target cells expressing BST1.These bispecific molecules target BST1 expressing cells to effector celland trigger CD3 or CD5-mediated effector cell activities, such as T cellclonal expansion and T cell cytotoxicity. In this embodiment, thebispecific antibody of the invention may have a total of either two orthree antibody variable domains, wherein first portion of the bispecificantibody is capable of recruiting the activity of a human immuneeffector cell by specifically binding to an effector antigen located onthe human immune effector cell, in which the effector antigen is thehuman CD3 or CD5 antigen, said first portion consisting of one antibodyvariable domain, and a second portion of the bispecific antibody iscapable of specifically binding to a target antigen other than theeffector antigen e.g. BST1, said target antigen being located on atarget cell other than said human immune effector cell, and said secondportion comprising one or two antibody variable domains.

In an embodiment of the invention in which the bispecific molecule ismultispecific, the molecule can further include a third bindingspecificity, in addition to an anti-Fc binding specificity or anti-CD3or CD5 binding specificity and an anti-BST1 binding specificity. In oneembodiment, the third binding specificity is an anti-enhancement factor(EF) portion, e.g. a molecule which binds to a surface protein involvedin cytotoxic activity and thereby increases the immune response againstthe target cell. The “anti-enhancement factor portion” can be anantibody, functional antibody fragment or a ligand that binds to a givenmolecule, e.g. an antigen or a receptor, and thereby results in anenhancement of the effect of the binding determinants for the Fcreceptor or target cell antigen. The “anti-enhancement factor portion”can bind an Fc receptor or a target cell antigen. Alternatively, theanti-enhancement factor portion can bind to an entity that is differentfrom the entity to which the first and second binding specificitiesbind. For example, the anti-enhancement factor portion can bind acytotoxic T-cell (e.g. via CD2, CD3, CD8, CD28, CD4, CD40, ICAM-1 orother immune cell that results in an increased immune response againstthe target cell).

In one embodiment, the bispecific molecules of the invention comprise asa binding specificity at least one antibody, or an antibody fragmentthereof, including, e.g. an Fab, Fab′, F(ab′)₂, Fv, Fd, dAb or a singlechain Fv. The antibody may also be a light chain or heavy chain dimer,or any minimal fragment thereof such as an Fv or a single chainconstruct as described in U.S. Pat. No. 4,946,778, the contents of whichis expressly incorporated by reference.

In one embodiment, the binding specificity for an Fcγ receptor isprovided by a monoclonal antibody, the binding of which is not blockedby human immunoglobulin G (IgG). As used herein, the term “IgG receptor”refers to any of the eight γ-chain genes located on chromosome 1. Thesegenes encode a total of twelve transmembrane or soluble receptorisoforms which are grouped into three Fcγ receptor classes: FcγRI(CD64), FcγRII (CD32), and FcγRIII (CD16). In one preferred embodiment,the Fcγ receptor is a human high affinity FcγRI. The human FcγRI is a 72kDa molecule, which shows high affinity for monomeric IgG (10⁸-10⁹ M⁻¹).

The production and characterization of certain preferred anti-Fcγmonoclonal antibodies are described in PCT Publication WO 88/00052 andin U.S. Pat. No. 4,954,617, the teachings of which are fullyincorporated by reference herein. These antibodies bind to an epitope ofFcγRI, FcγRII or FcγRIII at a site which is distinct from the Fcγbinding site of the receptor and, thus, their binding is not blockedsubstantially by physiological levels of IgG. Specific anti-FcγRIantibodies useful in this invention are mAb 22, mAb 32, mAb 44, mAb 62and mAb 197. The hybridoma producing mAb 32 is available from theAmerican Type Culture Collection, ATCC Accession No. HB9469. In otherembodiments, the anti-Fcγ receptor antibody is a humanized form ofmonoclonal antibody 22 (H22). The production and characterization of theH22 antibody is described in Graziano, R. F. et al. (1995) J. Immunol155 (10): 4996-5002 and PCT Publication WO 94/10332. The H22 antibodyproducing cell line was deposited at the American Type CultureCollection under the designation HA022CL1 and has the accession no. CRL11177.

In still other preferred embodiments, the binding specificity for an Fcreceptor is provided by an antibody that binds to a human IgA receptor,e.g. an Fc-alpha receptor [FcαRI (CD89)], the binding of which ispreferably not blocked by human immunoglobulin A (IgA). The term “IgAreceptor” is intended to include the gene product of one α-gene (FcαRI)located on chromosome 19. This gene is known to encode severalalternatively spliced transmembrane isoforms of 55 to 110 kDa. FcαRI(CD89) is constitutively expressed on monocytes/macrophages,eosinophilic and neutrophilic granulocytes, but not on non-effector cellpopulations. FcαRI has medium affinity (≈5×10⁷ M⁻¹) for both IgA1 andIgA2, which is increased upon exposure to cytokines such as G-CSF orGM-CSF [Morton, H. C. et al. (1996) Critical Reviews in Immunology16:423-440]. Four FcαRI-specific monoclonal antibodies, identified asA3, A59, A62 and A77, which bind FcαRI outside the IgA ligand bindingdomain, have been described [Monteiro, R. C. et al. (1992) J. Immunol.148:1764].

FcαRI and FcγRI are preferred trigger receptors for use in thebispecific molecules of the invention because they are (1) expressedprimarily on immune effector cells, e.g. monocytes, PMNs, macrophagesand dendritic cells; (2) expressed at high levels (e.g. 5,000-100,000per cell); (3) mediators of cytotoxic activities (e.g. ADCC,phagocytosis); and (4) mediate enhanced antigen presentation ofantigens, including self-antigens, targeted to them.

Antibodies which can be employed in the bispecific molecules of theinvention are murine, human, chimeric and humanized monoclonalantibodies.

The bispecific molecules of the present invention can be prepared byconjugating the constituent binding specificities, e.g. the anti-FcR,anti-CD3, anti-CD5 and anti-BST1 binding specificities, using methodsknown in the art. For example, the binding specificity of eachbispecific molecule can be generated separately and then conjugated toone another. When the binding specificities are proteins or peptides, avariety of coupling or cross-linking agents can be used for covalentconjugation. Examples of cross-linking agents include protein A,carbodiimide, N-succinimidyl-5-acetyl-thioacetate (SATA),5,5′-dithiobis(2-nitrobenzoic acid) (DTNB), o-phenylenedimaleimide(oPDM), N-succinimidyl-3-(2-pyridyldithio)propionate (SPDP), andsulfosuccinimidyl 4-(N-maleimidomethyl)cyclohaxane-1-carboxylate(sulfo-SMCC) [see e.g. Karpovsky et al. (1984) J. Exp. Med. 160:1686;Liu, M A et al. (1985) Proc. Natl. Acad. Sci. USA 82:8648]. Othermethods include those described in Paulus (1985) Behring Ins. Mitt. No.78, 118-132; Brennan et al. (1985) Science 229:81-83, and Glennie et al.(1987) J. Immunol. 139: 2367-2375. Preferred conjugating agents are SATAand sulfo-SMCC, both available from Pierce Chemical Co. (Rockford,Ill.)].

Additional bivalent work has been done for bispecifics by engineeringdual binding into full length antibody-like formats (Wu et al., 2007,Nature Biotechnology 25[11]:1290-1297; U.S. Ser. No. 12/477,711;Michaelson et al., 2009, mAbs 1[2]:128-141; PCT/US2008/074693; Zuo etal., 2000, Protein Engineering 13[5]:361-367; U.S. Ser. No. 09/865,198;Shen et al., 2006, J Biol Chem 281[16]:10706-10714; Lu et al., 2005, JBiol Chem 280[20]:19665-19672; PCT/US2005/025472; expressly incorporatedherein by reference).

When the binding specificities are antibodies, they can be conjugatedvia sulfhydryl bonding of the C-terminus hinge regions of the two heavychains. In a particularly preferred embodiment, the hinge region ismodified to contain an odd number of sulfhydryl residues, preferablyone, prior to conjugation.

Alternatively, both binding specificities can be encoded in the samevector and expressed and assembled in the same host cell. This method isparticularly useful where the bispecific molecule is a mAb×mAb, mAb×Fab,Fab×F(ab′)₂ or ligand x Fab fusion protein. A bispecific molecule of theinvention can be a single chain molecule comprising one single chainantibody and a binding determinant, or a single chain bispecificmolecule comprising two binding determinants. Bispecific molecules maycomprise at least two single chain molecules. Methods for preparingbispecific molecules are described for example in U.S. Pat. Nos.5,260,203; 5,455,030; 4,881,175; 5,132,405; 5,091,513; 5,476,786;5,013,653; 5,258,498; and 5,482,858, all of which are expresslyincorporated herein by reference.

Binding of the bispecific molecules to their specific targets can beconfirmed by, for example, enzyme-linked immunosorbent assay (ELISA),radioimmunoassay (RIA), FACS analysis, bioassay (e.g. growthinhibition), or Western Blot assay. Each of these assays generallydetects the presence of protein-antibody complexes of particularinterest by employing a labeled reagent (e.g. an antibody) specific forthe complex of interest. For example, the FcR-antibody complexes can bedetected using e.g. an enzyme-linked antibody or antibody fragment whichrecognizes and specifically binds to the antibody-FcR complexes.Alternatively, the complexes can be detected using any of a variety ofother immunoassays. For example, the antibody can be radioactivelylabeled and used in a radioimmunoassay (RIA) (see, for example,Weintraub, B., Principles of Radioimmunoassays, Seventh Training Courseon Radioligand Assay Techniques, The Endocrine Society, March, 1986,which is incorporated by reference herein). The radioactive isotope canbe detected by such means as the use of a γ counter or a scintillationcounter or by autoradiography.

Antibody Fragments and Antibody Mimetics

The instant invention is not limited to traditional antibodies and maybe practiced through the use of antibody fragments and antibodymimetics. As detailed below, a wide variety of antibody fragments andantibody mimetic technologies has now been developed and are widelyknown in the art. While a number of these technologies, such as domainantibodies, Nanobody®, and Unibody® make use of fragments of, or othermodifications to, traditional antibody structures, there are alsoalternative technologies, such as Affibody®, DARPin®, Anticalin®,Avimer®, and Versabody® that employ binding structures that, while theymimic traditional antibody binding, are generated from and function viadistinct mechanisms.

Domain antibodies (dAbs) are the smallest functional binding units ofantibodies, corresponding to the variable regions of either the heavy(V_(H)) or light (V_(L)) chains of human antibodies. Domain Antibodieshave a molecular weight of approximately 13 kDa. Domantis has developeda series of large and highly functional libraries of fully human V_(H)and V_(L) dAbs (more than ten billion different sequences in eachlibrary), and uses these libraries to select dAbs that are specific totherapeutic targets. In contrast to many conventional antibodies, domainantibodies are well expressed in bacterial, yeast, and mammalian cellsystems. Further details of domain antibodies and methods of productionthereof may be obtained by reference to U.S. Pat. Nos. 6,291,158;6,582,915; 6,593,081; 6,172,197; 6,696,245; US Serial No. 2004/0110941;European patent application No. 1433846 and European Patents 0368684 &0616640; WO05/035572, WO04/101790, WO04/081026, WO04/058821, WO04/003019and WO03/002609, each of which is herein incorporated by reference inits entirety.

Nanobody® are antibody-derived therapeutic proteins that contain theunique structural and functional properties of naturally-occurringheavy-chain antibodies. These heavy-chain antibodies contain a singlevariable domain (VHH) and two constant domains (C_(H)2 and C_(H)3).Importantly, the cloned and isolated VHH domain is a perfectly stablepolypeptide harboring the full antigen-binding capacity of the originalheavy-chain antibody. Nanobody® have a high homology with the V_(H)domains of human antibodies and can be further humanized without anyloss of activity. Importantly, Nanobody® have a low immunogenicpotential, which has been confirmed in primate studies with Nanobody®lead compounds.

Nanobody® combine the advantages of conventional antibodies withimportant features of small molecule drugs. Like conventionalantibodies, Nanobody® show high target specificity, high affinity fortheir target and low inherent toxicity. However, like small moleculedrugs they can inhibit enzymes and readily access receptor clefts.Furthermore, Nanobody® are extremely stable, can be administered bymeans other than injection (see e.g. WO 04/041867, which is hereinincorporated by reference in its entirety) and are easy to manufacture.Other advantages of Nanobody® include recognizing uncommon or hiddenepitopes as a result of their small size, binding into cavities oractive sites of protein targets with high affinity and selectivity dueto their unique 3-dimensional, drug format flexibility, tailoring ofhalf-life and ease and speed of drug discovery.

Nanobody® are encoded by single genes and are efficiently produced inalmost all prokaryotic and eukaryotic hosts e.g. E. coli (see e.g. U.S.Pat. No. 6,765,087, which is herein incorporated by reference in itsentirety), molds (for example Aspergillus or Trichoderma) and yeast (forexample Saccharomyces, Kluyveromyces, Hansenula or Pichia) (see e.g.U.S. Pat. No. 6,838,254, which is herein incorporated by reference inits entirety). The production process is scalable and multi-kilogramquantities of Nanobody® have been produced. Since Nanobody® exhibit asuperior stability compared with conventional antibodies, they can beformulated as a long shelf-life, ready-to-use solution.

The Nanoclone method (see e.g. WO 06/079372, which is hereinincorporated by reference in its entirety) is a proprietary method forgenerating Nanobody® against a desired target, based on automatedhigh-throughout selection of B-cells and could be used in the context ofthe instant invention.

Unibody® are another antibody fragment technology; however this one isbased upon the removal of the hinge region of IgG4 antibodies. Thedeletion of the hinge region results in a molecule that is essentiallyhalf the size of traditional IgG4 antibodies and has a univalent bindingregion rather than the bivalent binding region of IgG4 antibodies. It isalso well known that IgG4 antibodies are inert and thus do not interactwith the immune system, which may be advantageous for the treatment ofdiseases where an immune response is not desired, and this advantage ispassed onto Unibody®. For example, Unibody® may function to inhibit orsilence, but not kill, the cells to which they are bound. Additionally,Unibody® binding to cancer cells do not stimulate them to proliferate.Furthermore, because Unibody® are about half the size of traditionalIgG4 antibodies, they may show better distribution over larger solidtumors with potentially advantageous efficacy. Unibody® are cleared fromthe body at a similar rate to whole IgG4 antibodies and are able to bindwith a similar affinity for their antigens as whole antibodies. Furtherdetails of Unibody® may be obtained by reference to patent publicationWO2007/059782, which is herein incorporated by reference in itsentirety.

Affibody® molecules represent a new class of affinity proteins based ona 58-amino acid residue protein domain, derived from one of theIgG-binding domains of staphylococcal protein A. This three helix bundledomain has been used as a scaffold for the construction of combinatorialphagemid libraries, from which Affibody® variants that target thedesired molecules can be selected using phage display technology [NordK, Gunneriusson E, Ringdahl J, Stahl S, Uhlen M, Nygren P A (1997)‘Binding proteins selected from combinatorial libraries of an α-helicalbacterial receptor domain’ Nat Biotechnol 15:772-7. Ronmark J, GronlundH, Uhlen M, Nygren P A (2002) ‘Human immunoglobulin A (IgA)-specificligands from combinatorial engineering of protein A’ Eur J Biochem.269:2647-55.]. The simple, robust structure of Affibody® molecules incombination with their low molecular weight (6 kDa), make them suitablefor a wide variety of applications, for instance, as detection reagents[Ronmark J. et al. (2002) ‘Construction and characterization ofAffibody®-Fc chimeras produced in Escherichia coli’ J Immunol Methods261:199-211] and to inhibit receptor interactions [Sandstorm K, Xu Z,Forsberg G, Nygren P A (2003) ‘Inhibition of the CD28-CD80co-stimulation signal by a CD28-binding Affibody® ligand developed bycombinatorial protein engineering’ Protein Eng 16:691-7]. Furtherdetails of Affibody® and methods of production thereof may be obtainedby reference to U.S. Pat. No. 5,831,012 which is herein incorporated byreference in its entirety.

Labeled Affibody® may also be useful in imaging applications fordetermining abundance of isoforms.

DARPin® (Designed Ankyrin Repeat Proteins) are one example of anantibody mimetic DRP (Designed Repeat Protein) technology that has beendeveloped to exploit the binding abilities of non-antibody polypeptides.Repeat proteins such as ankyrin or leucine-rich repeat proteins, areubiquitous binding molecules, which occur, unlike antibodies, intra- andextracellularly. Their unique modular architecture features repeatingstructural units (repeats), which stack together to form elongatedrepeat domains displaying variable and modular target-binding surfaces.Based on this modularity, combinatorial libraries of polypeptides withhighly diversified binding specificities can be generated. This strategyincludes the consensus design of self-compatible repeats displayingvariable surface residues and their random assembly into repeat domains.

DARPin® can be produced in bacterial expression systems at very highyields and they belong to the most stable proteins known. Highlyspecific, high-affinity DARPin® to a broad range of target proteins,including human receptors, cytokines, kinases, human proteases, virusesand membrane proteins, have been selected. DARPin® having affinities inthe single-digit nanomolar to picomolar range can be obtained.

DARPin® have been used in a wide range of applications, including ELISA,sandwich ELISA, flow cytometric analysis (FACS), immunohistochemistry(IHC), chip applications, affinity purification or Western blotting.DARPin® also proved to be highly active in the intracellularcompartment, for example, as intracellular marker proteins fused togreen fluorescent protein (GFP). DARPin® were further used to inhibitviral entry with IC50 in the pM range. DARPin® are not only ideal toblock protein-protein interactions, but also to inhibit enzymes.Proteases, kinases and transporters have been successfully inhibited,most often an allosteric inhibition mode. Very fast and specificenrichments on the tumor and very favorable tumor to blood ratios makeDARPin® well suited for in vivo diagnostics or therapeutic approaches.

Additional information regarding DARPin® and other DRP technologies canbe found in US Patent Application Publication No. 2004/0132028, andInternational Patent Publication No. WO 02/20565, both of which arehereby incorporated by reference in their entirety.

Anticalin® are an additional antibody mimetic technology. However inthis case the binding specificity is derived from lipocalins, a familyof low molecular weight proteins that are naturally and abundantlyexpressed in human tissues and body fluids. Lipocalins have evolved toperform a range of functions in vivo associated with the physiologicaltransport and storage of chemically sensitive or insoluble compounds.Lipocalins have a robust intrinsic structure comprising a highlyconserved β-barrel which supports four loops at one terminus of theprotein. These loops form the entrance to a binding pocket andconformational differences in this part of the molecule account for thevariation in binding specificity between individual lipocalins.

While the overall structure of hypervariable loops supported by aconserved β-sheet framework is reminiscent of immunoglobulins,lipocalins differ considerably from antibodies in terms of size, beingcomposed of a single polypeptide chain of 160-180 amino acids which ismarginally larger than a single immunoglobulin domain.

Lipocalins are cloned and their loops are subjected to engineering inorder to create Anticalin®. Libraries of structurally diverse Anticalin®have been generated and Anticalin® display allows the selection andscreening of binding function, followed by the expression and productionof soluble protein for further analysis in prokaryotic or eukaryoticsystems. Studies have successfully demonstrated that Anticalin® can bedeveloped that are specific for virtually any human target protein canbe isolated and binding affinities in the nanomolar or higher range canbe obtained.

Anticalin® can also be formatted as dual targeting proteins, so-calledDuocalin®. A Duocalin® binds two separate therapeutic targets in oneeasily produced monomeric protein using standard manufacturing processeswhile retaining target specificity and affinity regardless of thestructural orientation of its two binding domains.

Modulation of multiple targets through a single molecule is particularlyadvantageous in diseases known to involve more than a single causativefactor. Moreover, bi- or multivalent binding formats such as Duocalin®have significant potential in targeting cell surface molecules indisease, mediating agonistic effects on signal transduction pathways orinducing enhanced internalization effects via binding and clustering ofcell surface receptors. Furthermore, the high intrinsic stability ofDuocalin® is comparable to monomeric Anticalin®, offering flexibleformulation and delivery potential for Duocalin®.

Additional information regarding Anticalin® can be found in U.S. Pat.No. 7,250,297 and International Patent Publication No. WO 99/16873, bothof which are hereby incorporated by reference in their entirety.

Another antibody mimetic technology useful in the context of the instantinvention are Avimer®. Avimer® are evolved from a large family of humanextracellular receptor domains by in vitro exon shuffling and phagedisplay, generating multidomain proteins with binding and inhibitoryproperties. Linking multiple independent binding domains has been shownto create avidity and results in improved affinity and specificitycompared with conventional single-epitope binding proteins. Otherpotential advantages include simple and efficient production ofmultitarget-specific molecules in Escherichia coli, improvedthermostability and resistance to proteases. Avimer® with sub-nanomolaraffinities have been obtained against a variety of targets.

Additional information regarding Avimer® can be found in US PatentApplication Publication Nos. 2006/0286603, 2006/0234299, 2006/0223114,2006/0177831, 2006/0008844, 2005/0221384, 2005/0164301, 2005/0089932,2005/0053973, 2005/0048512, 2004/0175756, all of which are herebyincorporated by reference in their entirety.

Versabody® are another antibody mimetic technology that could be used inthe context of the instant invention. Versabody® are small proteins of3-5 kDa with >15% cysteines, which form a high disulfide densityscaffold, replacing the hydrophobic core that typical proteins have. Thereplacement of a large number of hydrophobic amino acids, comprising thehydrophobic core, with a small number of disulfides results in a proteinthat is smaller, more hydrophilic (less aggregation and non-specificbinding), more resistant to proteases and heat, and has a lower densityof T-cell epitopes, because the residues that contribute most to MHCpresentation are hydrophobic. All four of these properties arewell-known to affect immunogenicity, and together they are expected tocause a large decrease in immunogenicity.

The inspiration for Versabody® comes from the natural injectablebiopharmaceuticals produced by leeches, snakes, spiders, scorpions,snails, and anemones, which are known to exhibit unexpectedly lowimmunogenicity. Starting with selected natural protein families, bydesign and by screening the size, hydrophobicity, proteolytic antigenprocessing and epitope density are minimized to levels far below theaverage for natural injectable proteins.

Given the structure of Versabody®, these antibody mimetics offer aversatile format that includes multi-valency, multi-specificity, adiversity of half-life mechanisms, tissue targeting modules and theabsence of the antibody Fc region. Furthermore, Versabody® aremanufactured in E. coli at high yields, and because of theirhydrophilicity and small size, Versabody® are highly soluble and can beformulated to high concentrations. Versabody® are exceptionally heatstable (they can be boiled) and offer extended shelf-life.

Additional information regarding Versabody® can be found in US PatentApplication Publication No. 2007/0191272 which is hereby incorporated byreference in its entirety.

The detailed description of antibody fragment and antibody mimetictechnologies provided above is not intended to be a comprehensive listof all technologies that could be used in the context of the instantspecification. For example, and also not by way of limitation, a varietyof additional technologies including alternative polypeptide-basedtechnologies, such as fusions of complimentary determining regions asoutlined in Qui et al. (2007) Nature Biotechnology 25(8):921-929, whichis hereby incorporated by reference in its entirety, as well as nucleicacid-based technologies, such as the RNA aptamer technologies describedin U.S. Pat. Nos. 5,789,157, 5,864,026, 5,712,375, 5,763,566, 6,013,443,6,376,474, 6,613,526, 6,114,120, 6,261,774, and 6,387,620, all of whichare hereby incorporated by reference, could be used in the context ofthe instant invention.

Pharmaceutical Compositions

In another aspect, the present invention provides a composition, e.g. apharmaceutical composition, containing one or a combination ofmonoclonal antibodies, or antigen-binding portion(s) thereof, of thepresent invention, formulated together with a pharmaceuticallyacceptable carrier. Such compositions may include one or a combinationof (e.g. two or more different) antibodies, or immunoconjugates orbispecific molecules of the invention. For example, a pharmaceuticalcomposition of the invention can comprise a combination of antibodies(or immunoconjugates or bispecifics) that bind to different epitopes onthe target antigen or that have complementary activities.

Pharmaceutical compositions of the invention also can be administered incombination therapy, i.e. combined with other agents. For example, thecombination therapy can include an anti-antibody of the presentinvention combined with at least one other anti-tumor agent, or ananti-inflammatory or immunosuppressant agent. Examples of therapeuticagents that can be used in combination therapy are described in greaterdetail below in the section on uses of the antibodies of the invention.

As used herein, “pharmaceutically acceptable carrier” includes any andall solvents, dispersion media, coatings, antibacterial and antifungalagents, isotonic and absorption delaying agents, and the like that arephysiologically compatible. Preferably, the carrier is suitable forintravenous, intramuscular, subcutaneous, parenteral, spinal orepidermal administration (e.g. by injection or infusion). Depending onthe route of administration, the active compound, i.e. antibody,immunoconjugate, or bispecific molecule, may be coated in a material toprotect the compound from the action of acids and other naturalconditions that may inactivate the compound.

The pharmaceutical compounds of the invention may include one or morepharmaceutically acceptable salts. A “pharmaceutically acceptable salt”refers to a salt that retains the desired biological activity of theparent compound and does not impart any undesired toxicological effects[see, e.g. Berge, S. M., et al. (1977) J. Pharm. Sci. 66:1-19]. Examplesof such salts include acid addition salts and base addition salts. Acidaddition salts include those derived from nontoxic inorganic acids, suchas hydrochloric, nitric, phosphoric, sulfuric, hydrobromic, hydroiodic,phosphorous and the like, as well as from nontoxic organic acids such asaliphatic mono- and dicarboxylic acids, phenyl-substituted alkanoicacids, hydroxy alkanoic acids, aromatic acids, aliphatic and aromaticsulfonic acids and the like. Base addition salts include those derivedfrom alkaline earth metals, such as sodium, potassium, magnesium,calcium and the like, as well as from nontoxic organic amines, such asN,N′-dibenzylethylenediamine, N-methylglucamine, chloroprocaine,choline, diethanolamine, ethylenediamine, procaine and the like.

A pharmaceutical composition of the invention also may include apharmaceutically acceptable anti-oxidant. Examples of pharmaceuticallyacceptable antioxidants include: (1) water soluble antioxidants, such asascorbic acid, cysteine hydrochloride, sodium bisulfate, sodiummetabisulfite, sodium sulfite and the like; (2) oil-solubleantioxidants, such as ascorbyl palmitate, butylated hydroxyanisole(BHA), butylated hydroxytoluene (BHT), lecithin, propyl gallate,alpha-tocopherol, and the like; and (3) metal chelating agents, such ascitric acid, ethylenediamine tetraacetic acid (EDTA), sorbitol, tartaricacid, phosphoric acid, and the like.

Examples of suitable aqueous and nonaqueous carriers that may beemployed in the pharmaceutical compositions of the invention includewater, ethanol, polyols (such as glycerol, propylene glycol,polyethylene glycol, and the like), and suitable mixtures thereof,vegetable oils, such as olive oil, and injectable organic esters, suchas ethyl oleate. Proper fluidity can be maintained, for example, by theuse of coating materials, such as lecithin, by the maintenance of therequired particle size in the case of dispersions, and by the use ofsurfactants.

These compositions may also contain adjuvants such as preservatives,wetting agents, emulsifying agents and dispersing agents. Prevention ofpresence of microorganisms may be ensured both by sterilizationprocedures, supra, and by the inclusion of various antibacterial andantifungal agents, for example, paraben, chlorobutanol, phenol sorbicacid, and the like. It may also be desirable to include isotonic agents,such as sugars, sodium chloride, and the like into the compositions. Inaddition, prolonged absorption of the injectable pharmaceutical form maybe brought about by the inclusion of agents which delay absorption suchas aluminum monostearate and gelatin.

Pharmaceutically acceptable carriers include sterile aqueous solutionsor dispersions and sterile powders for the extemporaneous preparation ofsterile injectable solutions or dispersion. The use of such media andagents for pharmaceutically active substances is known in the art.Except insofar as any conventional media or agent is incompatible withthe active compound, use thereof in the pharmaceutical compositions ofthe invention is contemplated. Supplementary active compounds can alsobe incorporated into the compositions.

Therapeutic compositions typically must be sterile and stable under theconditions of manufacture and storage. The composition can be formulatedas a solution, microemulsion, liposome, or other ordered structuresuitable to high drug concentration. The carrier can be a solvent ordispersion medium containing, for example, water, ethanol, polyol (forexample, glycerol, propylene glycol, and liquid polyethylene glycol, andthe like), and suitable mixtures thereof. The proper fluidity can bemaintained, for example, by the use of a coating such as lecithin, bythe maintenance of the required particle size in the case of dispersionand by the use of surfactants. In many cases, it will be preferable toinclude isotonic agents, for example, sugars, polyalcohols such asmannitol, sorbitol, or sodium chloride in the composition. Prolongedabsorption of the injectable compositions can be brought about byincluding in the composition an agent that delays absorption, forexample, monostearate salts and gelatin.

Sterile injectable solutions can be prepared by incorporating the activecompound in the required amount in an appropriate solvent with one or acombination of ingredients enumerated above, as required, followed bysterilization microfiltration. Generally, dispersions are prepared byincorporating the active compound into a sterile vehicle that contains abasic dispersion medium and the required other ingredients from thoseenumerated above. In the case of sterile powders for the preparation ofsterile injectable solutions, the preferred methods of preparation arevacuum drying and freeze-drying (lyophilization) that yield a powder ofthe active ingredient plus any additional desired ingredient from apreviously sterile-filtered solution thereof.

The amount of active ingredient which can be combined with a carriermaterial to produce a single dosage form will vary depending upon thesubject being treated, and the particular mode of administration. Theamount of active ingredient which can be combined with a carriermaterial to produce a single dosage form will generally be that amountof the composition which produces a therapeutic effect. Generally, outof 100 percent, this amount will range from about 0.01 percent to about99 percent of active ingredient, preferably from about 0.1 percent toabout 70 percent, most preferably from about 1 percent to about 30percent of active ingredient in combination with a pharmaceuticallyacceptable carrier.

Dosage regimens are adjusted to provide the optimum desired response(e.g. a therapeutic response). For example, a single bolus may beadministered, several divided doses may be administered over time or thedose may be proportionally reduced or increased as indicated by theexigencies of the therapeutic situation. It is especially advantageousto formulate parenteral compositions in dosage unit form for ease ofadministration and uniformity of dosage. Dosage unit form as used hereinrefers to physically discrete units suited as unitary dosages for thesubjects to be treated; each unit contains a predetermined quantity ofactive compound calculated to produce the desired therapeutic effect inassociation with the required pharmaceutical carrier. The specificationfor the dosage unit forms of the invention are dictated by and directlydependent on (a) the unique characteristics of the active compound andthe particular therapeutic effect to be achieved, and (b) thelimitations inherent in the art of compounding such an active compoundfor the treatment of sensitivity in individuals.

For administration of the antibody, the dosage ranges from about 0.0001to 100 mg/kg, and more usually 0.01 to 5 mg/kg, of the host body weight.For example dosages can be 0.3 mg/kg body weight, 1 mg/kg body weight, 3mg/kg body weight, 5 mg/kg body weight or 10 mg/kg body weight or withinthe range of 1-10 mg/kg. An exemplary treatment regime entailsadministration once per week, once every two weeks, once every threeweeks, once every four weeks, once a month, once every 3 months or onceevery three to 6 months. Preferred dosage regimens for an anti-BST1antibody of the invention include 1 mg/kg body weight or 3 mg/kg bodyweight via intravenous administration, with the antibody being givenusing one of the following dosing schedules: (i) every four weeks forsix dosages, then every three months; (ii) every three weeks; (iii) 3mg/kg body weight once followed by 1 mg/kg body weight every threeweeks.

In some methods, two or more monoclonal antibodies with differentbinding specificities are administered simultaneously, in which case thedosage of each antibody administered falls within the ranges indicated.Antibody is usually administered on multiple occasions. Intervalsbetween single dosages can be, for example, weekly, monthly, every threemonths or yearly. Intervals can also be irregular as indicated bymeasuring blood levels of antibody to the target antigen in the patient.In some methods, dosage is adjusted to achieve a plasma antibodyconcentration of about 1-1000 μg/ml and in some methods about 25-300μg/ml.

Alternatively, antibody can be administered as a sustained releaseformulation, in which case less frequent administration is required.Dosage and frequency vary depending on the half-life of the antibody inthe patient. In general, human antibodies show the longest half life,followed by humanized antibodies, chimeric antibodies, and nonhumanantibodies. The dosage and frequency of administration can varydepending on whether the treatment is prophylactic or therapeutic. Inprophylactic applications, a relatively low dosage is administered atrelatively infrequent intervals over a long period of time. Somepatients continue to receive treatment for the rest of their lives. Intherapeutic applications, a relatively high dosage at relatively shortintervals is sometimes required until progression of the disease isreduced or terminated, and preferably until the patient shows partial orcomplete amelioration of symptoms of disease. Thereafter, the patientcan be administered a prophylactic regime.

Actual dosage levels of the active ingredients in the pharmaceuticalcompositions of the present invention may be varied so as to obtain anamount of the active ingredient which is effective to achieve thedesired therapeutic response for a particular patient, composition, andmode of administration, without being toxic to the patient. The selecteddosage level will depend upon a variety of pharmacokinetic factorsincluding the activity of the particular compositions of the presentinvention employed, or the ester, salt or amide thereof, the route ofadministration, the time of administration, the rate of excretion of theparticular compound being employed, the duration of the treatment, otherdrugs, compounds and/or materials used in combination with theparticular compositions employed, the age, sex, weight, condition,general health and prior medical history of the patient being treated,and like factors well known in the medical arts.

A “therapeutically effective dosage” of an anti-BST1 antibody of theinvention preferably results in a decrease in severity of diseasesymptoms, an increase in frequency and duration of disease symptom-freeperiods, or a prevention of impairment or disability due to the diseaseaffliction. For example, for the treatment of the BST1 mediated tumors,a “therapeutically effective dosage” preferably inhibits cell growth ortumor growth by at least about 20%, more preferably by at least about40%, even more preferably by at least about 60%, and still morepreferably by at least about 80% relative to untreated subjects. Theability of a compound to inhibit tumor growth can be evaluated in ananimal model system predictive of efficacy in human tumors.Alternatively, this property of a composition can be evaluated byexamining the ability of the compound to inhibit cell growth, suchinhibition can be measured in vitro by assays known to the skilledpractitioner. A therapeutically effective amount of a therapeuticcompound can decrease tumor size, or otherwise ameliorate symptoms in asubject. One of ordinary skill in the art would be able to determinesuch amounts based on such factors as the subject's size, the severityof the subject's symptoms, and the particular composition or route ofadministration selected.

A composition of the present invention can be administered via one ormore routes of administration using one or more of a variety of methodsknown in the art. As will be appreciated by the skilled artisan, theroute and/or mode of administration will vary depending upon the desiredresults. Preferred routes of administration for antibodies of theinvention include intravenous, intramuscular, intradermal,intraperitoneal, subcutaneous, spinal or other parenteral routes ofadministration, for example by injection or infusion. The phrase“parenteral administration” as used herein means modes of administrationother than enteral and topical administration, usually by injection, andincludes, without limitation, intravenous, intramuscular, intraarterial,intrathecal, intracapsular, intraorbital, intracardiac, intradermal,intraperitoneal, transtracheal, subcutaneous, subcuticular,intraarticular, subcapsular, subarachnoid, intraspinal, epidural andintrasternal injection and infusion.

Alternatively, an antibody of the invention can be administered via anon-parenteral route, such as a topical, epidermal or mucosal route ofadministration, for example, intranasally, orally, vaginally, rectally,sublingually or topically.

The active compounds can be prepared with carriers that will protect thecompound against rapid release, such as a controlled releaseformulation, including implants, transdermal patches, andmicroencapsulated delivery systems. Biodegradable, biocompatiblepolymers can be used, such as ethylene vinyl acetate, polyanhydrides,polyglycolic acid, collagen, polyorthoesters, and polylactic acid. Manymethods for the preparation of such formulations are patented orgenerally known to those skilled in the art [see, e.g. Sustained andControlled Release Drug Delivery Systems (1978) J. R. Robinson, ed.,Marcel Dekker, Inc., N.Y].

Therapeutic compositions can be administered with medical devices knownin the art. For example, in a preferred embodiment, a therapeuticcomposition of the invention can be administered with a needlelesshypodermic injection device, such as the devices disclosed in U.S. Pat.Nos. 5,399,163; 5,383,851; 5,312,335; 5,064,413; 4,941,880; 4,790,824;or 4,596,556. Examples of well-known implants and modules useful in thepresent invention include: U.S. Pat. No. 4,487,603, which discloses animplantable micro-infusion pump for dispensing medication at acontrolled rate; U.S. Pat. No. 4,486,194, which discloses a therapeuticdevice for administering medicants through the skin; U.S. Pat. No.4,447,233, which discloses a medication infusion pump for deliveringmedication at a precise infusion rate; U.S. Pat. No. 4,447,224, whichdiscloses a variable flow implantable infusion apparatus for continuousdrug delivery; U.S. Pat. No. 4,439,196, which discloses an osmotic drugdelivery system having multi-chamber compartments; and U.S. Pat. No.4,475,196, which discloses an osmotic drug delivery system. Thesepatents are incorporated herein by reference. Many other such implants,delivery systems, and modules are known to those skilled in the art.

In certain embodiments, the monoclonal antibodies of the invention canbe formulated to ensure proper distribution in vivo. For example, theblood-brain barrier (BBB) excludes many highly hydrophilic compounds. Toensure that the therapeutic compounds of the invention cross the BBB (ifdesired), they can be formulated, for example, in liposomes. For methodsof manufacturing liposomes, see, e.g. U.S. Pat. Nos. 4,522,811;5,374,548; and 5,399,331. The liposomes may comprise one or moremoieties which are selectively transported into specific cells ororgans, thus enhance targeted drug delivery [see, e.g. V. V. Ranade(1989) J. Clin. Pharmacol. 29:685]. Exemplary targeting moieties includefolate or biotin (see, e.g. U.S. Pat. No. 5,416,016.); mannosides[Umezawa et al. (1988) Biochem. Biophys. Res. Commun. 153:1038];antibodies [P. G. Bloeman et al. (1995) FEBS Lett. 357:140; M. Owais etal. (1995) Antimicrob. Agents Chemother. 39:180]; surfactant protein Areceptor [Briscoe et al. (1995) Am. J. Physiol. 1233:134]; p120[Schreier et al. (1994) J. Biol. Chem. 269:9090]; see also K. Keinanen;M. L. Laukkanen (1994) FEBS Lett. 346:123; J. J. Killion; I. J. Fidler(1994) Immunomethods 4:273.

Uses and Methods

The antibodies, antibody compositions and methods of the presentinvention have numerous in vitro and in vivo diagnostic and therapeuticutilities involving the diagnosis and treatment of BST1 mediateddisorders.

In some embodiments, these molecules can be administered to cells inculture, in vitro or ex vivo, or to human subjects, e.g. in vivo, totreat, prevent and to diagnose a variety of disorders. As used herein,the term “subject” is intended to include human and non-human animals.Non-human animals include all vertebrates, e.g. mammals and non-mammals,such as non-human primates, sheep, dogs, cats, cows, horses, chickens,amphibians, and reptiles. Preferred subjects include human patientshaving disorders mediated by BST1 activity. The methods are particularlysuitable for treating human patients having a disorder associated withthe aberrant BST1 expression. When antibodies to BST1 are administeredtogether with another agent, the two can be administered in either orderor simultaneously.

Given the specific binding of the antibodies of the invention for BST1,the antibodies of the invention can be used to specifically detect BST1expression on the surface of cells and, moreover, can be used to purifyBST1 via immunoaffinity purification.

Furthermore, given the expression of BST1 on tumor cells, theantibodies, antibody compositions and methods of the present inventioncan be used to treat a subject with a tumorigenic disorder, e.g. adisorder characterized by the presence of tumor cells expressing BST1including, for example acute myeloid leukemia (AML), B-cell chroniclymphocytic leukemia, breast cancer, colorectal cancer, kidney cancer,head and neck cancer, lung cancer, ovarian cancer and pancreatic cancer.BST1 has been demonstrated to be internalised on antibody binding asillustrated in Example 5 below, thus enabling the antibodies of theinvention to be used in any payload mechanism of action e.g. an ADCapproach, radioimmunoconjugate, or ADEPT approach.

In one embodiment, the antibodies (e.g. monoclonal antibodies,multispecific and bispecific molecules and compositions) of theinvention can be used to detect levels of BST1, or levels of cells whichcontain BST1 on their membrane surface, which levels can then be linkedto certain disease symptoms. Alternatively, the antibodies can be usedto inhibit or block BST1 function which, in turn, can be linked to theprevention or amelioration of certain disease symptoms, therebyimplicating the BST1 as a mediator of the disease. This can be achievedby contacting a sample and a control sample with the anti-BST1 antibodyunder conditions that allow for the formation of a complex between theantibody and BST1. Any complexes formed between the antibody and theBST1 are detected and compared in the sample and the control.

In another embodiment, the antibodies (e.g. monoclonal antibodies,multispecific and bispecific molecules and compositions) of theinvention can be initially tested for binding activity associated withtherapeutic or diagnostic use in vitro. For example, compositions of theinvention can be tested using the flow cytometric assays described inthe Examples below.

The antibodies (e.g. monoclonal antibodies, multispecific and bispecificmolecules, immunoconjugates and compositions) of the invention haveadditional utility in therapy and diagnosis of BST1 related diseases.For example, the monoclonal antibodies, the multispecific or bispecificmolecules and the immunoconjugates can be used to elicit in vivo or invitro one or more of the following biological activities: to inhibit thegrowth of and/or kill a cell expressing BST1; to mediate phagocytosis orADCC of a cell expressing BST1 in the presence of human effector cells,or to block BST1 ligand binding to BST1.

In a particular embodiment, the antibodies (e.g. monoclonal antibodies,multispecific and bispecific molecules and compositions) are used invivo to treat, prevent or diagnose a variety of BST1-related diseases.Examples of BST1-related diseases include, among others, human cancertissues representing acute myeloid leukemia (AML), B-cell chroniclymphocytic leukemia, breast cancer, colorectal cancer, kidney cancer,head and neck cancer, lung cancer, ovarian cancer and pancreatic cancer.

Suitable routes of administering the antibody compositions (e.g.monoclonal antibodies, multispecific and bispecific molecules andimmunoconjugates) of the invention in vivo and in vitro are well knownin the art and can be selected by those of ordinary skill. For example,the antibody compositions can be administered by injection (e.g.intravenous or subcutaneous). Suitable dosages of the molecules usedwill depend on the age and weight of the subject and the concentrationand/or formulation of the antibody composition.

As previously described, the anti-BST1 antibodies of the invention canbe co-administered with one or other more therapeutic agents, e.g. acytotoxic agent, a radiotoxic agent or an immunosuppressive agent. Theantibody can be linked to the agent (as an immunocomplex) or can beadministered separate from the agent. In the latter case (separateadministration), the antibody can be administered before, after orconcurrently with the agent or can be co-administered with other knowntherapies, e.g. an anti-cancer therapy, e.g. radiation. Such therapeuticagents include, among others, anti-neoplastic agents such as doxorubicin(adriamycin), cisplatin bleomycin sulfate, carmustine, chlorambucil, andcyclophosphamide hydroxyurea which, by themselves, are only effective atlevels which are toxic or subtoxic to a patient. Cisplatin isintravenously administered as a 100 mg/kg dose once every four weeks andadriamycin is intravenously administered as a 60-75 mg/ml dose onceevery 21 days. Other agents suitable for co-administration with theantibodies of the invention include other agents used for the treatmentof cancers, e.g. acute myeloid leukemia (AML), B-cell chroniclymphocytic leukemia, breast cancer, colorectal cancer, kidney cancer,head and neck cancer, lung cancer, ovarian cancer or pancreatic cancer,such as Avastin®, 5FU and gemcitabine. Co-administration of theanti-BST1 antibodies or antigen binding fragments thereof, of thepresent invention with chemotherapeutic agents provides two anti-canceragents which operate via different mechanisms which yield a cytotoxiceffect to human tumor cells. Such co-administration can solve problemsdue to development of resistance to drugs or a change in theantigenicity of the tumor cells which would render them unreactive withthe antibody.

Target-specific effector cells, e.g. effector cells linked tocompositions (e.g. monoclonal antibodies, multispecific and bispecificmolecules) of the invention can also be used as therapeutic agents.Effector cells for targeting can be human leukocytes such asmacrophages, neutrophils or monocytes. Other cells include eosinophils,natural killer cells and other IgG- or IgA-receptor bearing cells. Ifdesired, effector cells can be obtained from the subject to be treated.The target-specific effector cells can be administered as a suspensionof cells in a physiologically acceptable solution. The number of cellsadministered can be in the order of 10⁸-10⁹, but will vary depending onthe therapeutic purpose. In general, the amount will be sufficient toobtain localization at the target cell, e.g. a tumor cell expressingBST1, and to affect cell killing by, e.g. phagocytosis. Routes ofadministration can also vary.

Therapy with target-specific effector cells can be performed inconjunction with other techniques for removal of targeted cells. Forexample, anti-tumor therapy using the compositions (e.g. monoclonalantibodies, multispecific and bispecific molecules) of the inventionand/or effector cells armed with these compositions can be used inconjunction with chemotherapy. Additionally, combination immunotherapymay be used to direct two distinct cytotoxic effector populations towardtumor cell rejection. For example, anti-BST1 antibodies linked toanti-Fc-gamma R1 or anti-CD3 may be used in conjunction with IgG- orIgA-receptor specific binding agents.

Bispecific and multispecific molecules of the invention can also be usedto modulate FcγR or FcγR levels on effector cells, such as by cappingand elimination of receptors on the cell surface. Mixtures of anti-Fcreceptors can also be used for this purpose.

The compositions (e.g. monoclonal antibodies, multispecific andbispecific molecules and immunoconjugates) of the invention which havecomplement binding sites, such as portions from IgG1, -2, or -3 or IgMwhich bind complement, can also be used in the presence of complement.In one embodiment, ex vivo treatment of a population of cells comprisingtarget cells with a binding agent of the invention and appropriateeffector cells can be supplemented by the addition of complement orserum containing complement. Phagocytosis of target cells coated with abinding agent of the invention can be improved by binding of complementproteins. In another embodiment target cells coated with thecompositions (e.g. monoclonal antibodies, multispecific and bispecificmolecules) of the invention can also be lysed by complement. In yetanother embodiment, the compositions of the invention do not activatecomplement.

The compositions (e.g. monoclonal antibodies, multispecific andbispecific molecules and immunoconjugates) of the invention can also beadministered together with complement. In certain embodiments, theinstant disclosure provides compositions comprising antibodies,multispecific or bispecific molecules and serum or complement. Thesecompositions can be advantageous when the complement is located in closeproximity to the antibodies, multispecific or bispecific molecules.Alternatively, the antibodies, multispecific or bispecific molecules ofthe invention and the complement or serum can be administeredseparately.

Also within the scope of the present invention are kits comprising theantibody compositions of the invention (e.g. monoclonal antibodies,bispecific or multispecific molecules, or immunoconjugates) andinstructions for use. The kit can further contain one or more additionalreagents, such as an immunosuppressive reagent, a cytotoxic agent or aradiotoxic agent, or one or more additional antibodies of the invention(e.g. an antibody having a complementary activity which binds to anepitope in the BST1 antigen distinct from the first antibody).

Accordingly, patients treated with antibody compositions of theinvention can be additionally administered (prior to, simultaneouslywith, or following administration of an antibody of the invention) withanother therapeutic agent, such as a cytotoxic or radiotoxic agent,which enhances or augments the therapeutic effect of the antibodies.

In other embodiments, the subject can be additionally treated with anagent that modulates, e.g. enhances or inhibits, the expression oractivity of Fcγ or Fcγ receptors by, for example, treating the subjectwith a cytokine. Preferred cytokines for administration during treatmentwith the multispecific molecule include of granulocytecolony-stimulating factor (G-CSF), granulocyte-macrophagecolony-stimulating factor (GM-CSF), interferon-γ (IFN-γ), and tumornecrosis factor (TNF).

The compositions (e.g. antibodies, multispecific and bispecificmolecules) of the invention can also be used to target cells expressingFcγR or BST1, for example, for labeling such cells. For such use, thebinding agent can be linked to a molecule that can be detected. Thus,the invention provides methods for localizing ex vivo or in vitro cellsexpressing Fc receptors, such as FcγR, or BST1. The detectable label canbe, e.g. a radioisotope, a fluorescent compound, an enzyme, or an enzymeco-factor.

In a particular embodiment, the invention provides methods for detectingthe presence of the BST1 antigen in a sample, or measuring the amount ofthe BST1 antigen, comprising contacting the sample, and a controlsample, with a monoclonal antibody, or an antigen binding portionthereof, which specifically binds to BST1, under conditions that allowfor formation of a complex between the antibody or portion thereof andBST1. The formation of a complex is then detected, wherein a differencecomplex formation between the sample compared to the control sample isindicative the presence of the BST1 antigen in the sample.

In other embodiments, the invention provides methods for treating a BST1mediated disorder in a subject, e.g. human cancers and humaninflammatory disease, including the diseases of the invention.

In yet another embodiment, immunoconjugates of the invention can be usedto target compounds (e.g. therapeutic agents, labels, cytotoxins,radiotoxins immunosuppressants, etc.) to cells which have BST1 cellsurface receptors by linking such compounds to the antibody. Forexample, an anti-BST1 antibody can be conjugated to any of the toxincompounds described in U.S. Pat. Nos. 6,281,354 and 6,548,530, US patentpublication Nos. 2003/0050331, 2003/0064984, 2003/0073852, and2004/0087497, or published in WO 03/022806. Thus, the invention alsoprovides methods for localizing ex vivo or in vivo cells expressing BST1(e.g. with a detectable label, such as a radioisotope, a fluorescentcompound, an enzyme, or an enzyme co-factor). Alternatively, theimmunoconjugates can be used to kill cells which have BST1 cell surfacereceptors by targeting cytotoxins or radiotoxins to BST1.

All references cited in this specification, including without limitationall papers, publications, patents, patent applications, presentations,texts, reports, manuscripts, brochures, books, internet postings,journal articles, periodicals, product fact sheets, and the like, onehereby incorporated by reference into this specification in theirentireties. The discussion of the references herein is intended tomerely summarize the assertions made by their authors and no admissionis made that any reference constitutes prior art and Applicants' reservethe right to challenge the accuracy and pertinence of the citedreferences.

Although the foregoing invention has been described in some detail byway of illustration and example for purposes of clarity ofunderstanding, it will be readily apparent to those of ordinary skill inthe art in light of the teachings of this invention that certain changesand modifications may be made thereto without departing from the spiritor scope of the dependant claims.

The present invention is further illustrated by the following exampleswhich should not be construed as further limiting.

Example 1 Construction of a Phage-Display Library

A recombinant protein composed of amino acids 29-292 of BST1 (SEQ IDNO:44) was eurkaryotically synthesized by standard recombinant methodsand used as antigen for immunization.

Immunization and mRNA Isolation

A phage display library for identification of the BST1-binding moleculeswas constructed as follows. An mice (Jackson Laboratories, Bar Harbor,Me.) were immunized intraperitoneally with the recombinant BST1 antigen(the extracellular domain), using 100 μg protein in Freund's completeadjuvant, on day 0, and with 100 μg antigen on day 28. Test bleeds ofmice were obtained through puncture of the retro-orbital sinus. If, bytesting the titers, they were deemed high by ELISA using thebiotinylated BST1 antigen immobilized via neutravidin (Reacti-Bind™)NeutrAvidin™-Coated Polystyrene Plates, Pierce, Rockford, Ill.), themice were boosted with 100 μg of protein on day 70, 71 and 72, withsubsequent sacrifice and splenectomy on day 77. If titers of antibodywere not deemed satisfactory, mice were boosted with 100 μg antigen onday 56 and a test bleed taken on day 63. If satisfactory titers wereobtained, the animals were boosted with 100 μg of antigen on day 98, 99,and 100 and the spleens harvested on day 105.

The spleens were harvested in a laminar flow hood and transferred to apetri dish, trimming off and discarding fat and connective tissue. Thespleens were macerated quickly with the plunger from a sterile 5 ccsyringe in the presence of 1.0 ml of solution D (25.0 g guanidinethiocyanate (Boehringer Mannheim, Indianapolis, Ind.), 29.3 ml sterilewater, 1.76 ml 0.75 M sodium citrate pH 7.0, 2.64 ml 10% sarkosyl(Fisher Scientific, Pittsburgh, Pa.), 0.36 ml 2-mercaptoethanol (FisherScientific, Pittsburgh, Pa.). This spleen suspension was pulled throughan 18 gauge needle until all cells were lysed and the viscous solutionwas transferred to a microcentrifuge tube. The petri dish was washedwith 100 μl of solution D to recover any remaining spleen. Thissuspension was then pulled through a 22 gauge needle an additional 5-10times.

The sample was divided evenly between two microcentrifuge tubes and thefollowing added, in order, with mixing by inversion after each addition:50 μl 2 M sodium acetate pH 4.0, 0.5 ml water-saturated phenol (FisherScientific, Pittsburgh, Pa.), 100 μl chloroform/isoamyl alcohol 49:1(Fisher Scientific, Pittsburgh, Pa.). The solution was vortexed for 10sec and incubated on ice for 15 min. Following centrifugation at 14 krpmfor 20 min at 2-8° C., the aqueous phase was transferred to a freshtube. An equal volume of water saturated phenol:chloroform:isoamylalcohol (50:49:1) was added, and the tube vortexed for ten seconds.After 15 min incubation on ice, the sample was centrifuged for 20 min at2-8° C., and the aqueous phase transferred to a fresh tube andprecipitated with an equal volume of isopropanol at −20° C. for aminimum of 30 min. Following centrifugation at 14 krpm for 20 min at 4°C., the supernatant was aspirated away, the tubes briefly spun and alltraces of liquid removed from the RNA pellet.

The RNA pellets were each dissolved in 300 μl of solution D, combined,and precipitated with an equal volume of isopropanol at −20° C. for aminimum of 30 min. The sample was centrifuged 14 krpm for 20 min at 4°C., the supernatant aspirated as before, and the sample rinsed with 100μl of ice-cold 70% ethanol. The sample was again centrifuged 14 krpm for20 min at 4° C., the 70% ethanol solution aspirated, and the RNA pelletdried in vacuo. The pellet was resuspended in 100 μl of sterile diethylpyrocarbonate-treated water. The concentration was determined by A260using an absorbance of 1.0 for a concentration of 40 μg/ml. The RNAswere stored at −80° C.

Preparation of Complementary DNA (cDNA)

The total RNA purified from mouse spleens as described above was useddirectly as template for cDNA preparation. RNA (50 μg) was diluted to100 μL with sterile water, and 10 μL of 130 ng/μL oligo dT12(synthesized on Applied Biosystems Model 392 DNA synthesizer) was added.The sample was heated for 10 min at 70° C., then cooled on ice. Forty μL5* first strand buffer was added (Gibco/BRL, Gaithersburg, Md.), alongwith 20 μL 0.1 M dithiothreitol (Gibco/BRL, Gaithersburg, Md.), 10 μL 20mM deoxynucleoside triphosphates (dNTP's, Boehringer Mannheim,Indianapolis, Ind.), and 10 μL water on ice. The sample was thenincubated at 37° C. for 2 min. Ten μL reverse transcriptase(Superscript™) II, Gibco/BRL, Gaithersburg, Md.) was added andincubation was continued at 37° C. for 1 hr. The cDNA products were useddirectly for polymerase chain reaction (PCR).

Amplification of Antibody Genes by PCR

To amplify substantially all of the H and L chain genes using PCR,primers were chosen that corresponded to substantially all publishedsequences. Because the nucleotide sequences of the amino termini of Hand L contain considerable diversity, 33 oligonucleotides weresynthesized to serve as 5′ primers for the H chains, and 29oligonucleotides were synthesized to serve as 5′ primers for the kappa Lchains as described in U.S. Pat. No. 6,555,310. The constant regionnucleotide sequences for each chain required only one 3′ primer for theH chains and one 3′ primer for the kappa L chains.

A 50 μL reaction was performed for each primer pair with 50 μmol of 5′primer, 50 μmol of 3′ primer, 0.25 μL Taq DNA Polymerase (5 units/μL,Boehringer Mannheim, Indianapolis, Ind.), 3 μL cDNA (prepared asdescribed), 5 μL 2 mM dNTP's, 5 μL 10*Taq DNA polymerase buffer withMgCl2 (Boehringer Mannheim, Indianapolis, Ind.), and H₂O to 50 μL.Amplification was done using a GeneAmp® 9600 thermal cycler (PerkinElmer, Foster City, Calif.) with the following thermocycle program: 94°C. for 1 min; 30 cycles of 94° C. for 20 sec, 55° C. for 30 sec, and 72°C. for 30 sec, 72° C. for 6 min; 4° C.

The dsDNA products of the PCR process were then subjected to asymmetricPCR using only a 3′ primer to generate substantially only the anti-sensestrand of the target genes. A 100 μL reaction was done for each dsDNAproduct with 200 μmol of 3′ primer, 2 μL of dsDNA product, 0.5 μL TaqDNA Polymerase, 10 μL 2 mM dNTP's, 10 μL 10*Taq DNA polymerase bufferwith MgCl₂ (Boehringer Mannheim, Indianapolis, Ind.), and H₂O to 100 μL.The same PCR program as that described above was used to amplify thesingle-stranded (ss)-DNA.

Purification of Single-Stranded DNA by High Performance LiquidChromatography and Kinasing Single-Stranded DNA

The H chain ss-PCR products and the L chain single-stranded PCR productswere ethanol precipitated by adding 2.5 volumes ethanol and 0.2 volumes7.5 M ammonium acetate and incubating at −20° C. for at least 30 min.The DNA was pelleted by centrifuging in an Eppendorf centrifuge at 14krpm for 10 min at 2-8° C. The supernatant was carefully aspirated, andthe tubes were briefly spun a 2nd time. The last drop of supernatant wasremoved with a pipette. The DNA was dried in vacuo for 10 min on mediumheat. The H chain products were pooled in 210 μL water and the L chainproducts were pooled separately in 210 μL water. The single-stranded DNAwas purified by high performance liquid chromatography (HPLC) using aHewlett Packard 1090 HPLC and a Gen-Pak™) FAX anion exchange column(Millipore Corp., Milford, Mass.). The gradient used to purify thesingle-stranded DNA is shown in Table 1, and the oven temperature was60° C. Absorbance was monitored at 260 nm. The single-stranded DNAeluted from the HPLC was collected in 0.5 min fractions. Fractionscontaining single-stranded DNA were ethanol precipitated, pelleted anddried as described above. The dried DNA pellets were pooled in 200 μLsterile water.

TABLE 1 HPLC gradient for purification of ss-DNA Time (min) % A % B % CFlow (ml/min) 0 70 30 0 0.75 2 40 60 0 0.75 17 15 85 0 0.75 18 0 100 00.75 23 0 100 0 0.75 24 0 0 100 0.75 28 0 0 100 0.75 29 0 100 0 0.75 340 100 0 0.75 35 70 30 0 0.75 Buffer A is 25 mM Tris, 1 mM EDTA, pH 8.0Buffer B is 25 mM Tris, 1 mM EDTA, 1M NaCl, pH 8.0 Buffer C is 40 mmphosphoric acid

The single-stranded DNA was 5′-phosphorylated in preparation formutagenesis. Twenty-four μL 10* kinase buffer (United StatesBiochemical, Cleveland, Ohio), 10.4 μL 10 mM adenosine-5′-triphosphate(Boehringer Mannheim, Indianapolis, Ind.), and 2 μL polynucleotidekinase (30 units/μL, United States Biochemical, Cleveland, Ohio) wasadded to each sample, and the tubes were incubated at 37° C. for 1 hr.The reactions were stopped by incubating the tubes at 70° C. for 10 min.The DNA was purified with one extraction of Tris equilibrated phenol(pH>8.0, United States Biochemical, Cleveland, Ohio):chloroform:isoamylalcohol (50:49:1) and one extraction with chloroform:isoamyl alcohol(49:1). After the extractions, the DNA was ethanol precipitated andpelleted as described above. The DNA pellets were dried, then dissolvedin 50 μL sterile water. The concentration was determined by measuringthe absorbance of an aliquot of the DNA at 260 nm using 33 μg/ml for anabsorbance of 1.0. Samples were stored at −20° C.

Preparation of Uracil Templates Used in Generation of Spleen AntibodyPhage Libraries

One ml of E. coli CJ236 (BioRAD, Hercules, Calif.) overnight culture wasadded to 50 ml 2*YT in a 250 ml baffled shake flask. The culture wasgrown at 37° C. to OD600=0.6, inoculated with 10 μl of a 1/100 dilutionof BS45 vector phage stock (described in U.S. Pat. No. 6,555,310) andgrowth continued for 6 hr. Approximately 40 ml of the culture wascentrifuged at 12 krpm for 15 min at 4° C. The supernatant (30 ml) wastransferred to a fresh centrifuge tube and incubated at room temperaturefor 15 min after the addition of 15 μl of 10 mg/ml RNaseA (BoehringerMannheim, Indianapolis, Ind.). The phages were precipitated by theaddition of 7.5 ml of 20% polyethylene glycol 8000 (Fisher Scientific,Pittsburgh, Pa.)/3.5M ammonium acetate (Sigma Chemical Co., St. Louis,Mo.) and incubation on ice for 30 min. The sample was centrifuged at 12krpm for 15 min at 2-8° C. The supernatant was carefully discarded, andthe tube briefly spun to remove all traces of supernatant. The pelletwas resuspended in 400 μl of high salt buffer (300 mM NaCl, 100 mM TrispH 8.0, 1 mM EDTA), and transferred to a 1.5 ml tube.

The phage stock was extracted repeatedly with an equal volume ofequilibrated phenol:chloroform:isoamyl alcohol (50:49:1) until no traceof a white interface was visible, and then extracted with an equalvolume of chloroform:isoamyl alcohol (49:1). The DNA was precipitatedwith 2.5 volumes of ethanol and ⅕ volume 7.5 M ammonium acetate andincubated 30 min at −20° C. The DNA was centrifuged at 14 krpm for 10min at 4° C., the pellet washed once with cold 70% ethanol, and dried invacuo. The uracil template DNA was dissolved in 30 μl sterile water andthe concentration determined by A260 using an absorbance of 1.0 for aconcentration of 40 μg/ml. The template was diluted to 250 ng/μL withsterile water, aliquoted and stored at −20° C.

Mutagenesis of Uracil Template with ss-DNA and Electroporation into E.coli to Generate Antibody Phage Libraries

Antibody phage display libraries were generated by simultaneouslyintroducing single-stranded heavy and light chain genes onto a phagedisplay vector uracil template. A typical mutagenesis was performed on a2 μg scale by mixing the following in a 0.2 ml PCR reaction tube: 8 μlof (250 ng/μL) uracil template, 8 μL of 10* annealing buffer (200 mMTris pH 7.0, 20 mM MgCl2, 500 mM NaCl), 3.33 μl of kinasedsingle-stranded heavy chain insert (100 ng/μL), 3.1 μl of kinasedsingle-stranded light chain insert (100 ng/μL), and sterile water to 80μl DNA was annealed in a GeneAmp® 9600 thermal cycler using thefollowing thermal profile: 20 sec at 94° C., 85° C. for 60 sec, 85° C.to 55° C. ramp over 30 min, hold at 55° C. for 15 min. The DNA wastransferred to ice after the program finished. The extension/ligationwas carried out by adding 8 μl of 10* synthesis buffer (5 mM each dNTP,10 mM ATP, 100 mM Tris pH 7.4, 50 mM MgCl₂, 20 mM DTT), 8 μL T4 DNAligase (1 U/μL, Boehringer Mannheim, Indianapolis, Ind.), 8 μL dilutedT7 DNA polymerase (1 U/μL, New England BioLabs, Beverly, Mass.) andincubating at 37° C. for 30 min. The reaction was stopped with 300 μL ofmutagenesis stop buffer (10 mM Tris pH 8.0, 10 mM EDTA). The mutagenesisDNA was extracted once with equilibrated phenol(pH>8):chloroform:isoamyl alcohol (50:49:1), once withchloroform:isoamyl alcohol (49:1), and the DNA was ethanol precipitatedat −20° C. for at least 30 min. The DNA was pelleted and the supernatantcarefully removed as described above. The sample was briefly spun againand all traces of ethanol removed with a pipetman. The pellet was driedin vacuo. The DNA was resuspended in 4 μL of sterile water.

One μL of mutagenesis DNA (500 ng) was transferred into 40 μlelectrocompetent E. coli DH12S (Gibco/BRL, Gaithersburg, Md.) usingelectroporation. The transformed cells were mixed with approximately 1.0ml of overnight XL-1 cells which were diluted with 2*YT broth to 60% theoriginal volume. This mixture was then transferred to a 15-ml sterileculture tube and 9 ml of top agar added for plating on a 150-mm LB agarplate. Plates were incubated for 4 hr at 37° C. and then transferred to20° C. overnight. First round antibody phage were made by eluting phageoff these plates in 10 ml of 2*YT, spinning out debris, and taking thesupernatant. These samples are the antibody phage display libraries usedfor selecting antibodies against the BST1. Efficiency of theelectroporations was measured by plating 10 μl of a 10⁻⁴ dilution ofsuspended cells on LB agar plates, follow by overnight incubation ofplates at 37° C. The efficiency was calculated by multiplying the numberof plaques on the 10⁻⁴ dilution plate by 106. Library electroporationefficiencies are typically greater than 1*10⁷ phages under theseconditions.

Transformation of E. coli by Electroporation

Electrocompetent E. coli cells were thawed on ice. DNA was mixed with 40L of these cells by gently pipetting the cells up and down 2-3 times,being careful not to introduce an air bubble. The cells were transferredto a Gene Pulser cuvette (0.2 cm gap, BioRAD, Hercules, Calif.) that hadbeen cooled on ice, again being careful not to introduce an air bubblein the transfer. The cuvette was placed in the E. coli Pulser (BioRAD,Hercules, Calif.) and electroporated with the voltage set at 1.88 kVaccording to the manufacturer's recommendation. The transformed samplewas immediately resuspended in 1 ml of 2*YT broth or 1 ml of a mixtureof 400 μl 2*YT/600 μl overnight XL-1 cells and processed as proceduresdictated.

Plating M13 Phage or Cells Transformed with Antibody Phage-DisplayVector Mutagenesis Reaction

Phage samples were added to 200 μL of an overnight culture of E. coliXL1-Blue when plating on 100 mm LB agar plates or to 600 μL of overnightcells when plating on 150 mm plates in sterile 15 ml culture tubes.After adding LB top agar (3 ml for 100 mm plates or 9 ml for 150 mmplates, top agar stored at 55° C. (see, Appendix A1, Sambrook et al.,supra.), the mixture was evenly distributed on an LB agar plate that hadbeen pre-warmed (37° C.-55° C.) to remove any excess moisture on theagar surface. The plates were cooled at room temperature until the topagar solidified. The plates were inverted and incubated at 37° C. asindicated.

Preparation of Biotinylated ADP-Ribosyl Cyclase 2 and BiotinylatedAntibodies

The concentrated recombinant BST1 antigen (full length extracellulardomain) was extensively dialyzed into BBS (20 mM borate, 150 mM NaCl,0.1% NaN₃, pH 8.0). After dialysis, 1 mg of the BST1 (1 mg/ml in BBS)was reacted with a 15 fold molar excess of biotin-XX-NHS ester(Molecular Probes, Eugene, Oreg., stock solution at 40 mM in DMSO). Thereaction was incubated at room temperature for 90 min and then quenchedwith taurine (Sigma Chemical Co., St. Louis, Mo.) at a finalconcentration of 20 mM. The biotinylation reaction mixture was thendialyzed against BBS at 2-8° C. After dialysis, the biotinylated BST1was diluted in panning buffer (40 mM Tris, 150 mM NaCl, 20 mg/ml BSA,0.1% Tween 20, pH 7.5), aliquoted, and stored at −80° C. until needed.

Antibodies were reacted with 3-(N-maleimidylpropionyl)biocytin(Molecular Probes, Eugene, Oreg.) using a free cysteine located at thecarboxy terminus of the heavy chain. Antibodies were reduced by addingDTT to a final concentration of 1 mM for 30 min at room temperature.Reduced antibody was passed through a Sephadex® G50 desalting columnequilibrated in 50 mM potassium phosphate, 10 mM boric acid, 150 mMNaCl, pH 7.0. 3-(N-maleimidylpropionyl)-biocytin was added to a finalconcentration of 1 mM and the reaction allowed to proceed at roomtemperature for 60 min. Samples were then dialyzed extensively againstBBS and stored at 2-8° C.

Preparation of Avidin Magnetic Latex

The magnetic latex (Estapor, 10% solids, Bangs Laboratories, Fishers,Ind.) was thoroughly resuspended and 2 ml aliquoted into a 15 ml conicaltube. The magnetic latex was suspended in 12 ml distilled water andseparated from the solution for 10 min using a magnet (PerSeptiveBiosystems, Framingham, Mass.). While maintaining the separation of themagnetic latex with the magnet, the liquid was carefully removed using a10 ml sterile pipette. This washing process was repeated an additionalthree times. After the final wash, the latex was resuspended in 2 ml ofdistilled water. In a separate 50 ml conical tube, 10 mg of avidin-HS(NeutrAvidin, Pierce, Rockford, Ill.) was dissolved in 18 ml of 40 mMTris, 0.15 M sodium chloride, pH 7.5 (TBS). While vortexing, the 2 ml ofwashed magnetic latex was added to the diluted avidin-HS and the mixturemixed an additional 30 sec. This mixture was incubated at 45° C. for 2hr, shaking every 30 min. The avidin magnetic latex was separated fromthe solution using a magnet and washed three times with 20 ml BBS asdescribed above. After the final wash, the latex was resuspended in 10ml BBS and stored at 4° C.

Immediately prior to use, the avidin magnetic latex was equilibrated inpanning buffer (40 mM Tris, 150 mM NaCl, 20 mg/ml BSA, 0.1% Tween 20, pH7.5). The avidin magnetic latex needed for a panning experiment (200μl/sample) was added to a sterile 15 ml centrifuge tube and brought to10 ml with panning buffer. The tube was placed on the magnet for 10 minto separate the latex. The solution was carefully removed with a 10 mlsterile pipette as described above. The magnetic latex was resuspendedin 10 ml of panning buffer to begin the second wash. The magnetic latexwas washed a total of 3 times with panning buffer. After the final wash,the latex was resuspended in panning buffer to the starting volume.

Example 2 Selection of Recombinant Polyclonal Antibodies to BST1 Antigen

Binding reagents that specifically bind to the BST1 were selected fromthe phage display libraries created from hyperimmunized mice asdescribed in Example 1.

Panning

First round antibody phage were prepared as described in Example 1 usingBS45 uracil template. Electroporations of mutagenesis DNA were performedyielding phage samples derived from different immunized mice. To createmore diversity in the recombinant polyclonal library, each phage samplewas panned separately.

Before the first round of functional panning with the biotinylated BST1antigen, antibody phage libraries were selected for phage displayingboth heavy and light chains on their surface by panning with7F11-magnetic latex (as described in Examples 21 and 22 of U.S. Pat. No.6,555,310). Functional panning of these enriched libraries was performedin principle as described in Example 16 of U.S. Pat. No. 6,555,310.Specifically, 10 μL of 1*10⁻⁶ M biotinylated BST1 antigen was added tothe phage samples (approximately 1*10⁻⁸ M final concentration of theBST1), and the mixture allowed to come to equilibrium overnight at 2-8°C.

After reaching equilibrium, samples were panned with avidin magneticlatex to capture antibody phage bound to the BST1. Equilibrated avidinmagnetic latex (Example 1), 200 μL latex per sample, was incubated withthe phage for 10 min at room temperature. After 10 min, approximately 9ml of panning buffer was added to each phage sample, and the magneticlatex separated from the solution using a magnet. After a ten minuteseparation, unbound phage was carefully removed using a 10 ml sterilepipette. The magnetic latex was then resuspended in 10 ml of panningbuffer to begin the second wash. The latex was washed a total of threetimes as described above. For each wash, the tubes were in contact withthe magnet for 10 min to separate unbound phage from the magnetic latex.After the third wash, the magnetic latex was resuspended in 1 ml ofpanning buffer and transferred to a 1.5 mL tube. The entire volume ofmagnetic latex for each sample was then collected and resuspended in 200μl 2*YT and plated on 150 mm LB plates as described in Example 1 toamplify bound phage. Plates were incubated at 37° C. for 4 hr, thenovernight at 20° C.

The 150 mm plates used to amplify bound phage were used to generate thenext round of antibody phage. After the overnight incubation, secondround antibody phage were eluted from the 150 mm plates by pipetting 10mL of 2*YT media onto the lawn and gently shaking the plate at roomtemperature for 20 min. The phage samples were then transferred to 15 mldisposable sterile centrifuge tubes with a plug seal cap, and the debrisfrom the LB plate pelleted by centrifuging the tubes for 15 min at 3500rpm. The supernatant containing the second round antibody phage was thentransferred to a new tube.

A second round of functional panning was set up by diluting 100 μL ofeach phage stock into 900 μL of panning buffer in 15 ml disposablesterile centrifuge tubes. The biotinylated BST1 antigen was then addedto each sample as described for the first round of panning, and thephage samples incubated for 1 hr at room temperature. The phage sampleswere then panned with avidin magnetic latex as described above. Theprogress of panning was monitored at this point by plating aliquots ofeach latex sample on 100 mm LB agar plates to determine the percentageof kappa positives. The majority of latex from each panning (99%) wasplated on 150 mm LB agar plates to amplify the phage bound to the latex.The 100 mm LB agar plates were incubated at 37° C. for 6-7 hr, afterwhich the plates were transferred to room temperature and nitrocellulosefilters (pore size 0.45 mm, BA85 Protran, Schleicher and Schuell, Keene,N.H.) were overlaid onto the plaques.

Plates with nitrocellulose filters were incubated overnight at roomtemperature and then developed with a goat anti-mouse kappa alkalinephosphatase conjugate to determine the percentage of kappa positives asdescribed below. Phage samples with lower percentages (<70%) of kappapositives in the population were subjected to a round of panning with7F11-magnetic latex before performing a third functional round ofpanning overnight at 2-8° C. using the biotinylated BST1 antigen atapproximately 2*10⁻⁹ M. This round of panning was also monitored forkappa positives. Individual phage samples that had kappa positivepercentages greater than 80% were pooled and subjected to a final roundof panning overnight at 2-8° C. at 5*10⁻⁹ M. The BST1 antibody genescontained within the eluted phage from this fourth round of functionalpanning were subcloned into the expression vector, pBRncoH3.

The subcloning process was done generally as described in Example 18 ofU.S. Pat. No. 6,555,310. After subcloning, the expression vector waselectroporated into DH10B cells and the mixture grown overnight in 2*YTcontaining 1% glycerol and 10 μg/ml tetracycline. After a second roundof growth and selection in tetracycline, aliquots of cells were frozenat −80° C. as the source for the BST1 polyclonal antibody production.Monoclonal antibodies were selected from these polyclonal mixtures byplating a sample of the mixture on LB agar plates containing 10 μg/mltetracycline and screening for antibodies that recognized the BST1.

Expression and Purification of Recombinant Antibodies AgainstADP-Ribosyl Cyclase 2

A shake flask inoculum was generated overnight from a −70° C. cell bankin an Innova 4330 incubator shaker (New Brunswick Scientific, Edison,N.J.) set at 37° C., 300 rpm. The inoculum was used to seed a 20 Lfermentor (Applikon, Foster City, Calif.) containing defined culturemedium [Pack et al. (1993) Bio/Technology 11: 1271-1277] supplementedwith 3 g/L L-leucine, 3 g/L L-isoleucine, 12 g/L casein digest (Difco,Detroit, Mich.), 12.5 g/L glycerol and 10 μg/ml tetracycline. Thetemperature, pH and dissolved oxygen in the fermentor were controlled at26° C., 6.0-6.8 and 25% saturation, respectively. Foam was controlled byaddition of polypropylene glycol (Dow, Midland, Mich.). Glycerol wasadded to the fermentor in a fed-batch mode. Fab expression was inducedby addition of L(+)-arabinose (Sigma, St. Louis, Mo.) to 2 g/L duringthe late logarithmic growth phase. Cell density was measured by opticaldensity at 600 nm in an UV-1201 spectrophotometer (Shimadzu, Columbia,Md.). Following run termination and adjustment of pH to 6.0, the culturewas passed twice through an M-210B-EH Microfluidizer (Microfluidics,Newton, Mass.) at 17,000 psi. The high pressure homogenization of thecells released the Fab into the culture supernatant.

The first step in purification was expanded bed immobilized metalaffinity chromatography (EB-IMAC). Streamline™ chelating resin(Pharmacia, Piscataway, N.J.) was charged with 0.1 M NiCl₂ and was thenexpanded and equilibrated in 50 mM acetate, 200 mM NaCl, 10 mMimidazole, 0.01% NaN₃, pH 6.0 buffer flowing in the upward direction. Astock solution was used to bring the culture homogenate to 10 mMimidazole, following which it was diluted two-fold or higher inequilibration buffer to reduce the wet solids content to less than 5% byweight. It was then loaded onto the Streamline column flowing in theupward direction at a superficial velocity of 300 cm/hr. The cell debrispassed through unhindered, but the Fab was captured by means of the highaffinity interaction between nickel and the hexahistidine tag on the Fabheavy chain. After washing, the expanded bed was converted to a packedbed and the Fab was eluted with 20 mM borate, 150 mM NaCl, 200 mMimidazole, 0.01% NaN₃, pH 8.0 buffer flowing in the downward direction.

The second step in the purification used ion-exchange chromatography(IEC). Q Sepharose® FastFlow resin (Pharmacia, Piscataway, N.J.) wasequilibrated in 20 mM borate, 37.5 mM NaCl, 0.01% NaN₃, pH 8.0. The Fabelution pool from the EB-IMAC step was diluted four-fold in 20 mMborate, 0.01% NaN₃, pH 8.0 and loaded onto the IEC column. Afterwashing, the Fab was eluted with a 37.5-200 mM NaCl salt gradient. Theelution fractions were evaluated for purity using an Xcell II™ SDS-PAGEsystem (Novex, San Diego, Calif.) prior to pooling. Finally, the Fabpool was concentrated and diafiltered into 20 mM borate, 150 mM NaCl,0.01% NaN₃, pH 8.0 buffer for storage. This was achieved in a SartoconSlice™ system fitted with a 10,000 MWCO cassette (Sartorius, Bohemia,N.Y.). The final purification yields were typically 50%. Theconcentration of the purified Fab was measured by UV absorbance at 280nm, assuming an absorbance of 1.6 for a 1 mg/ml solution.

Example 3 Specificity of Monoclonal Antibodies to BST1 Determined byFlow Cytometry Analysis

The specificity of antibodies against the BST1 selected in Example 2 wastested by flow cytometry. To test the ability of the antibodies to bindto the cell surface BST1 protein, the antibodies were incubated with theBST1-expressing cells, A549 and H226, from human lung adenocarcinoma andhuman lung squamous carcinoma, respectively. Cells were washed in FACSbuffer (DPBS, 2% FBS), centrifuged and resuspended in 1000 of thediluted primary BST1 antibody (also diluted in FACS buffer). Theantibody-A549 complex was incubated on ice for 60 min and then washedtwice with FACS buffer as described above. The cell-antibody pellet wasresuspended in 100 μl of the diluted secondary antibody (also diluted inFACS buffer) and incubated on ice for 60 min on ice. The pellet waswashed as before and resuspended in 2000 FACS buffer. The samples wereloaded onto the BD FACScanto II flow sytometer and the data analyzedusing the BD FACSdiva software.

Results

The results of the flow cytometry analysis demonstrated that 4monoclonal antibodies designated BST1_A1, BST1_A2 and BST_A3 boundeffectively to the cell-surface human BST1. FIG. 3 a shows the bindingspecificities of both BST1_A1 and BST1_A2 to BST1 on A549 and H226cells, respectively. FIG. 3 b shows the binding specificities BST1_A3 toBST1 on A549 and H226 cells. The results indicate strong binding ofthose antibodies against BST1 on A549 and H226.

Example 4 Structural Characterization of Monoclonal Antibodies to BST1

The cDNA sequences encoding the heavy and light chain variable regionsof the BST1_A2 and BST1_A1 monoclonal antibodies were obtained usingstandard PCR techniques and were sequenced using standard DNA sequencingtechniques.

The antibody sequences may be mutagenized to revert back to germlineresidues at one or more residues.

The nucleotide and amino acid sequences of the heavy chain variableregion of BST1_A2 are SEQ ID NO: 6 and 2, respectively.

The nucleotide and amino acid sequences of the light chain variableregion of BST1_A2 are SEQ ID NO: 8 and 4, respectively.

Comparison of the BST1_A2 heavy chain immunoglobulin sequence to theknown murine germline immunoglobulin heavy chain sequences demonstratedthat the BST1_A2 heavy chain utilizes a V_(H) segment from murinegermline V_(H) 1-39. Further analysis of the BST1_A2 V_(H) sequenceusing the Kabat system of CDR region determination led to thedelineation of the heavy chain CDR1, CDR2 and CDR3 regions as shown inSEQ ID NOs:10, 12, and 14, respectively. The alignments of the BST1_A2CDR1 and CDR2 V_(H) sequences to the germline V_(H) 1-39 sequence areshown in FIGS. 1 a and 1 b.

Comparison of the BST1_A2 light chain immunoglobulin sequence to theknown murine germline immunoglobulin light chain sequences demonstratedthat the BST1_A2 light chain utilizes a V_(K) segment from murinegermline V_(K) 4-55. Further analysis of the BST1_A2 V_(K) sequenceusing the Kabat system of CDR region determination led to thedelineation of the light chain CDR1, CDR2 and CDR3 regions as shown inSEQ ID NOs:16, 18, and 20, respectively. The alignments of the BST1_A2CDR1, CDR2 and CDR3 V_(K) sequences to the germline V_(K) 4-55 sequencesare shown in FIGS. 2 a, 2 b and 2 c.

The nucleotide and amino acid sequences of the heavy chain variableregion of BST1_A1 are SEQ ID NO: 5 and 1, respectively.

The nucleotide and amino acid sequences of the light chain variableregion of BST1_A1 are SEQ ID NO: 7 and 3, respectively.

Comparison of the BST1_A1 heavy chain immunoglobulin sequence to theknown murine germline immunoglobulin heavy chain sequences demonstratedthat the BST1_A1 heavy chain utilizes a V_(H) segment from murinegermline V_(H) 1-80. Further analysis of the BST1_A1 V_(H) sequenceusing the Kabat system of CDR region determination led to thedelineation of the heavy chain CDR1, CDR2 and CDR3 regions as shown inSEQ ID NOs:9, 11, and 13, respectively. The alignments of the BST1_A1CDR1 and CDR2 V_(H) sequences to the germline V_(H) 1-80 sequence areshown in FIGS. 1 a and 1 b.

Comparison of the BST1_A1 light chain immunoglobulin sequence to theknown murine germline immunoglobulin light chain sequences demonstratedthat the BST1_A1 light chain utilizes a V_(K) segment from murinegermline V_(K) 4-74. Further analysis of the BST1_A1 V_(K) sequenceusing the Kabat system of CDR region determination led to thedelineation of the light chain CDR1, CDR2 and CDR3 regions as shown inSEQ ID NOs:15, 17, and 19, respectively. The alignments of the BST1_A1CDR1, CDR2 and CDR3 V_(K) sequences to the germline V_(K) 4-74 sequencesare shown in FIGS. 2 a, 2 b and 2 c.

The nucleotide and amino acid sequences of the heavy chain variableregion of BST1_A3 are SEQ ID NO: 54 and 52, respectively.

The nucleotide and amino acid sequences of the light chain variableregion of BST1_A3 are SEQ ID NO: 55 and 53, respectively.

Comparison of the BST1_A3 heavy chain immunoglobulin sequence to theknown murine germline immunoglobulin heavy chain sequences demonstratedthat the BST1_A3 heavy chain utilizes a V_(H) segment from murine V_(H)germline 69-1. Further analysis of the BST1_A3 V_(H) sequence using theKabat system of CDR region determination led to the delineation of theheavy chain CDR1, CDR2 and CDR3 regions as shown in SEQ ID NOs: 56, 57and 58, respectively. The alignments of the BST1_A3 CDR1 and CDR2 V_(H)sequences to the murine V_(H) germline 69-1 sequence are shown in FIGS.1 a and 1 b.

Comparison of the BST1_A3 light chain immunoglobulin sequence to theknown murine germline immunoglobulin light chain sequences demonstratedthat the BST1_A3 light chain utilizes a V_(K) segment from murine V_(K)germline 44-1. Further analysis of the BST1_A3 V_(K) sequence using theKabat system of CDR region determination led to the delineation of thelight chain CDR1, CDR2 and CDR3 regions as shown in SEQ ID NOs: 59, 60and 61, respectively. The alignments of the BST1_A3 CDR1, CDR2 and CDR3V_(K) sequences to the murine V_(K) germline 44-1 sequences are shown inFIGS. 2 a, 2 b and 2 c.

Example 5 Internalization and MabZAP of BST1_A1 and BST1_A2 in A549 andH226 Cells

Internalization of BST1_A1 and BST1_A2 by H226 and A549 wereinvestigated using a MabZap assay. The MabZAP assay showedinternalization of the anti-BST1 monoclonal antibodies through bindingof an anti-human IgG secondary antibody conjugated to the toxin saporin.(Advanced Targeting System, San Diego, Calif., IT-22-100). First, BST1Fab was bound to the surface of the cells. Then, the MabZAP antibodieswere bound to the primary antibodies. Next, the MabZAP complex wasinternalized by the cells. The entrance of Saporin into the cellsresulted in protein synthesis inhibition and eventual cell death.

The MabZAP assay was conducted as follows. Each of the cells was seededat a density of 5×103 cells per well. The anti-BST1 monoclonal antibodyor an isotype control human IgG was serially diluted then added to thecells and incubated for 15 min at 25° C. The MabZAP was then added andincubated for 72 hr at 37° C. Cell viability in the plates was detectedby CellTiter-Glo® Luminescent Cell Viability Assay kit (Promega, G7571)and the plates were read and analysed using Promega Glomax. Cell deathwas proportional to the concentration of anti-BST1 monoclonalantibodies.

FIGS. 4 a and 4 b show that the anti-BST1 monoclonal antibodies, BST1_A1and BST1_A2 were internalized by and induced approximately 20% cell killat 10 nmol/L of H226 and A549 cells, as compared to the anti-human IgGisotype control antibody. The results show BST1_A1 and BST1_A2 can beinternalized at low levels and can induce cell kill at highconcentrations when coupled with a toxin.

Example 6 Humanization of BST1_A2

To design humanized sequences of BST1_A2 V_(H) and V_(L), the frameworkamino acids important for the formation of the CDR structure wereidentified using the three-dimensional model. Human V_(H) and V_(L),sequences with high homologies with BST1_A2 were also selected from theGenBank database. The CDR sequences together with the identifiedframework amino acid residues were grafted from BST1_A2 to the humanframework sequences (FIGS. 5-7).

Example 7 Antibody-Dependent Cellular Cytotoxicity Mediated by Anti-BST1mAbs

Firstly 25 μl of parental and Non-Fucosylated anti-BST1 antibodies(BST1_A2 and BST1_A2_NF) at concentrations ranging from 10 nm/L to 0.1nm/L were added to separate wells of a v bottom 96 well plate along with50 μl of BST1-expressing A549 and U937 cells. 25 μl of Effector cellswas then added to the wells to yield final effector:target (E:T) ratioof 10:1 and 25:1. The plate was then gently spun at 1000 rpm for 2minutes, after which it was incubated for 4 hrs in 37° C., 5% CO2incubator. At 3 hrs post incubation, 10 μl of lysis solution was addedto each of the wells containing BST1-expressing cells alone to measuremaximum LDH release, and one set of wells containing media alone forvolume correction control.

After the incubation, the cells were spun gently at 1000 rpm for 2minutes, after which 500 of supernatant was transferred to a flat bottom96 well plate. Using the CytoTox 96® Non-Radioactive Cytotoxicity Assayavailable from Promega (Cat #: G1780), kit components were reconstitutedaccording to manufacturer's specifications and 50 μl of the substratemix was then added to each well. The plate was then covered and left toincubate for 30 minutes at 25° C. protected from light. Following this,50 μl of Stop Solution was added to each well and the absorbance wasrecorded at 490 nm using the varioskan plate reader.

Using an antibody known to incite cell-kill via ADCC as a positivecontrol and a human IgG1 isotype control as a negative control, theresults show BST1_A2 and BST1_A2_NF were capable of eliciting ADCC onBST1-expressing A549 and U937 cells. On BST1-expressing A549 cells,BST1_A2_NF were shown to approximately 45% killing at 10 nmol/L (FIG. 8a). On BST1-expressing U937 cells, BST1_A2 were shown to approximately20% killing at 1 nmol/L and BST1_A2_NF were shown to approximately 45%killing at 1 nmol/L (FIG. 8 b).

Example 8 Specificity of Monoclonal Antibodies to BST1 Determined byFlow Cytometry Analysis in AML Patients

The ability of BST_A2 to bind to lymphoblasts from patients with AML wastested by Flow Cytometry Analysis. Blood was taken from 20 AML patients.Using the procedure as described in the Example 3, BST_A2 was shown tobind to AML blasts of approx. 80% of the AML patients.

Example 9 Immunohistochemistry Using BST1_A2_NF on Normal Tissue

BST1_A2_NF (Oxford BioTherapeutics, Lot 04302012), or an isotype controlantibody were diluted in SFPB (Dako, Carpinteria, Calif., X0909) toobtain a 20 μg/mL solution. The secondary antibody, goat anti-humanimmunoglobulin G (IgG) antigen-binding fragment (Fab) fluoresceinisothiocyanate (FITC)-conjugated (Jackson Immunoresearch, West Grove,Pa., 109-097-003), was similarly diluted to obtain a 20 μg/mL solution.

Primary and secondary antibodies were combined (50 μL each) in a labeledtube, gently mixed, and incubated for 3 minutes at room temperature,resulting in a primary antibody concentration of 10 μg/mL. This mixturewas diluted 1:5 with SFPB, gently mixed, and incubated for 30 minutes atroom temperature, resulting in a primary antibody concentration of 1μg/mL.

Slides

During the above incubations, the pre-fixed, frozen normal tissue arrayslide (Biochain Institute, Newark, Calif., T6234700), containing 20types of normal human organ tissue (adrenal, ovary, pancreas, thyroid,brain cerebrum, brain cerebellum, lung, spleen, uterus, cervix, breast,placenta, heart, skin, skeletal muscle, kidney, stomach, smallintestine, liver, salivary gland), and the FF H226 (ATCC, Manassas, Va.,CRL-5826) cell pellet sections (Biochain Institute, Newark, Calif.) wereremoved from the freezer (−80° C.) and allowed to thaw at roomtemperature for 20 minutes. The H226 slides were fixed for 10 min in icecold acetone and allowed to dry at room temperature for 15 min. Bothslides were then washed 3 times in Dulbecco's phosphate-buffered saline(DPBS, Thermo Scientific, Waltham Va., SH30028-03) for 5 minutes eachwashed, labeled, and the tissue was circled with a hydrophobic-barrierpen.

Endogenous peroxidase activity was inhibited by incubating the slideswith peroxidase suppressor solution (Thermo Scientific, 35000) for 10minutes. The slides were then washed once in DPBS, and once in DPBScontaining 0.125% Tween-20 v/v (DPBS-T, Fisher Scientific, Hampton,N.H., BP337-100) for 3 minutes each.

Staining Complexes

To produce the final staining complexes, a 10 μg/μL solution of humanIgG (Chrome pure human IgG, whole molecule, Jackson Immunoresearch,09-000-003) was prepared in SFPB and equal volume added to theprimary/secondary antibody mixture. This combination was gently mixedand incubated at room temperature for 30 minutes, resulting in a finalprimary antibody concentration of 1 μg/mL.

Immunolabelling

While the staining complexes were incubating, nonspecific binding siteson the tissues were blocked by incubating the slides in SFPB for 30minutes at room temperature in a humidified chamber. Afterwards, theblocking solution was removed and the staining complexes were added tothe tissue for 30 minutes at room temperature in a humidified chamber.The staining complexes were then removed and the slides were washed oncein DPBS and once in DPBS-T for 3 minutes each.

The tertiary antibody (mouse anti-FITC, Abcam, Cambridge, Mass.,ab10257) was diluted to a concentration of 2 μg/mL in SFPB and appliedto the slides for 30 minutes at room temperature in a humidifiedchamber. The tertiary antibody was removed and the slides were washedonce in DPBS and once in DPBS-T for 3 minutes each.

The quaternary antibody (Dual Link EnVision+HRP-conjugated polymer,Mouse and Rabbit Dako, K4063) was applied to the slides for 30 minutesat room temperature in a humidified chamber. The slides were washed oncein DPBS and once in DPBS-T for 3 minutes each.

To develop the slides, DAB chromogen (Invitrogen, Grand Island, N.Y.,882014) was prepared according to manufacturer instructions and appliedto the slides for 10 minutes at room temperature. The DAB reagent wasremoved to toxic waste and the slides were washed in tap water. Theslides were washed in DPBS for 3 min and then counterstained by a 30second incubation in Harris hematoxylin (Fisher, 23-245-677). Thehematoxylin was removed to waste and the slides were washed in runningtap water for 2 minutes and allowed to dry at room temperature. Coverslips were mounted with Faramount mounting media (Dako, 5302580) and thestaining was analyzed under light microscopy.

Results

FF H226 cell pellets and normal human tissues were assayed by IHC withBST1_A2_NF for expression of BST1. Normal human tissues assayed by IHCincluded adrenal, ovary, pancreas, thyroid, cerebrum, cerebellum, lung,spleen, uterus, cervix, breast, placenta, heart, skin, skeletal muscle,kidney, stomach, small intestine salivary gland and liver. H226 cells(known to express BST1) were used as a positive control for binding.Human IgG was used as a negative control antibody. H226 cell pelletsstained specifically for BST1. Staining can be seen in the cellcytoplasm, and also at the cell membrane on some cells. In contrast,specific BST1 staining was largely absent from an array of FF normalhuman tissues.

Example 10 Antibody-Dependent Cellular Cytotoxicity Mediated byBST1_A2_NF Using NK Cells from AML Patients

The ADCC activity of BST1_A2_NF was investigated using the AML cell lineU937 postitive for expression of BST1 and comparing effector cells fromhealthy donors and AML patients.

Target cells were labelled with ⁵¹Cr (˜50 μCi) for 90 minutes at 37° C.NK cells were isolated from healthy donor and AML patient PBMCs by CD56positive selection (NK-cell Isolation Kit; MACS Miltenyi Biotech) andadded to the target cells at different E:T Ratios (50:1 to 6.25:1) intriplicates. Antibody was added at a final concentration of 10 μg/ml.Target cells and NK cells without antibody served as negative control.ADCC on RAJI cells mediated by Rituximab and NK cells from the samehealthy donor and AML patient served as positive control. SpontaneousLysis (⁵¹CR labelled U937 cells without NK-cells and antibody) andMaximum Lysis (⁵¹CR labelled U937 cells directly on measurement plate)were determined in sextuplicates. After 4 hours incubation at 37° C.,supernatants were transferred to the measurement plate (Lumaplate),dried over night and analyzed using a TOPCount (Perkin Elmer) reader.Data were analyzed using the Graphpad PRISM Software Version 4.0.

Results

As shown in FIG. 9 a, NK cells from AML patients are shown to be highlyeffective in ADCC lysis of U937 cells, comparable to NK cells from ahealthy donor using BST1_A2_NF at 10 μg/ml antibody concentration. FIG.9 b shows NK cells from AML patients also appeared to be highlyeffective in ADCC lysis of RAJI cells using Rituximab, although lessactive than NK cells from healthy donors. The results show BST1_A2_NFwould have a therapeutic effect in AML patients.

Example 11 Antibody-Dependent Cell-Mediated Cytotoxicity of BST1_A2_NFAgainst Monocytes

Blood from 5 healthy donors, obtained as buffy coat from the StanfordUniversity Blood Bank (Palo Alto Calif.) was processed usingFicoll-Paque™ Plus density gradient medium (Amersham Biosciences,Uppsala, Sweden). Isolated PBMCs were washed twice withphosphate-buffered saline (PBS), and red blood cells (RBCs) were lysedwith 1×RBC Lysis Buffer (eBioscience, San Diego Calif.) according tomanufacturer instructions. PBMCs were washed twice more with PBS afterquenching the lysed cells with 10% fetal bovine serum (FBS). PBMCs werethen resuspended in 30 mL each PBS, counted, spun down, and resuspendedat 250,000 cells/100 μL Roswell Park Memorial Institute (RPMI) mediumplus sodium pyruvate, glutamine, and Pen Strep (penicillin streptomycin,Invitrogen); FBS was added to a final concentration of 10%.

BST1_A2_NF antibody was added in triplicate, starting at a concentrationof 5 μg/mL and diluted serially by 1:3-fold. Another non-fucosylatedantibody (6g11NF) and its parental form (6g11P) were included asnegative controls. The target antigen for 6g11 is not expressed onmonocytes. Other control wells included PBMCs alone. Plates were placedin a 5% humidified carbon dioxide incubator (standard tissue cultureconditions) for 15 to 20 hours. After the overnight incubation,triplicates were combined into a single sample for each condition. Cellswere spun for 5 minutes at 1000×g, resuspended in FACS buffer, washed,spun down, and resuspended in 100 μL FACS buffer and placed on ice. Eachwell (except for unstained controls) received 5 μLphycoerythrin-conjugated anti-CD33. After wells were incubated on icefor 45 minutes in the dark, cells were washed twice with FACS buffer,resuspended in 200 μL FACS buffer, and analyzed on a Guava EasyCyte™(EMD Millipore, Bellerica Mass.) flow cytometer.

The numbers of CD33 positive monocytes were recorded, and cytotoxicitydetermined by calculating the number of monocytes as a % of untreated(PBMCs only) at each antibody concentration.

Results

FIG. 10 displays the combined % cytotoxicity of three replicates at eachantibody concentration for each of 5 different healthy donors tested.The results show BST1_A2_NF promotes homogenous ADCC against monocytesin a dose-dependent manner. Non-targeting antibody, 6g11NF(non-fucosylated antibody) or its parent, 6g11P, had no effect onCD33-positive monocyte numbers. This shows BST1_A2_NF has the ability topromote target cell killing by effector cells in a dose dependentmanner.

Example 12 BST1_A2_NF Binds BST1 Cynomolgus Monkey Antigen-Transfected293FS

HEK293FS cells transfected with cynomolgus monkey CD157/BST1 protein(ADQ89190.1) were washed twice with PBS and re-suspended in FACS buffer(PBS+2% fetal bovine serum [FBS]). Cells were stained with either 0.25μg/mL BST1_A2_NF antibody or 0.25 μg/mL human IgG isotype controlantibody, followed by anti-human phycoerythrin secondary antibodies(Southern Biotech, Birmingham Ala.). Samples were analyzed on a GuavaEasycyte (Millipore) and the mean fluoresence intensity (MFI) recorded.

FIG. 11 a shows BST1_A2_NF binds BST1 cynomolgus monkeyantigen-transfected 293FS cells while untransfected 293FS cells (lipidonly) are not recognized by BST1_A2_NF.

The experiment was repeated with various concentrations of BST1_A2_NFfollowed by staining with anti-human phycoerythrin secondary antibody.The percentage of PE positive cells were plotted against antibodyconcentration. The titration curve depicted in FIG. 11 b showsBST1_A2_NF binding to BST1 cynomolgus monkey antigen-transfected HEK293FS cells. The EC₅₀ was determined to be 5 nM. The results showBST1_A2_NF antibody cross-reacts with cynomolgus monkey antigen ontransfected (overexpressing) cells.

Example 13 BST1_A2_NF Binds BST1 Antigen Endogenously Expressed onCynomolgus Monocytes

Guava 1× Lysing Solution (Millipore: 4700-0081) was added to bloodobtained from naïve cynomolgus monkeys in a ratio of 38 mL lysingsolution to 1 mL blood, mixed gently, and allowed to stand for 15minutes at room temperature. Cells remaining after RBC lysis were washedtwice in PBS, re-suspended in 10 mL FACS buffer (PBS plus 2% FBS), andplaced in wells (100 μL/well) for staining. Human AB serum was added toeach well to block Fc receptor binding Alexa Fluor® 488 CD11b antibody(cynomolgus cross-reactive clone, ICRF44, Becton Dickinson catalognumber 561687) was added to wells to stain monocytes and granulocytes.BST1_A2_NF conjugated to-PE was added to stain BST1-positive cells.Reactions were incubated on ice for 45 minutes, washed twice, andre-suspended in FACS buffer. Samples were analyzed on a Guava Easycyte(Millipore).

The results demonstrates co-staining of CD11b and BST1_A2_NF incynomolgus whole blood after RBC lysis, indicating that anti-humanBST1_A2_NF recognizes the BST1 antigen endogenously expressed oncynomolgus monocytes.

Example 14 An Exploratory Intravenous Infusion Toxicity Study ofBST1_A2_NF in Cynomolgus Monkeys with a 21-Day Recovery Period

Eight female monkeys were assigned to the study with 2 monkeys/group.Either Phosphate Buffered Saline (PBS) or BST1_A2_NF was administered bya 15-minute intravenous infusion on Days 1 (see Table 14.1) and 59 (seeTable 14.2) at a dose volume of 2.10 mL/kg.

Parameters evaluated included cageside and detailed observations, bodyweights and body weight changes, food consumption, clinical pathology(clinical chemistry, hematology, coagulation and urinalysis), grosspathology, selected microscopic pathology, toxicokinetics and functionalanalysis (depletion of monocytes/granulocytes and receptor occupancy) byfluorescence-activated cell sorting (FACS) assay.

Blood samples for clinical chemistry, hematology and urine analyses werecollected from all study animals during acclimation, prior to each dose(Days 1 and 58), 24, 48, 72 and 96 hours, 7 days, 10 days and 14 dayspost each dose; at 22 days post the first dose and then weeklythereafter until the second dose. Blood samples for coagulationevaluation were collected from all study animals during acclimation,prior to each dose (Days 1 and 58), and prior to necropsy (Day 80).Blood samples for toxicokinetic evaluations were collected from allstudy animals prior to each dose (Days 1 and 59), 24, 48, 72 and 96hours, 7 days, 10 days and 14 days post each dose; at 22 days post thefirst dose and then weekly thereafter until the second dose. Bloodsamples for FACS assay were collected from all study animals prior toeach dose (Days 1 and 58), 1, 3, 7, 11 and 14 days post each dose; at 22days post the first dose and then weekly thereafter until the seconddose; prior to necropsy (Day 80).

All study animals were euthanized and necropsied following the finalblood collection on Day 80.

Toxicokinetics

Plasma samples were received on dry ice and stored at −80° C. untilanalyzed. The ELISA assays were performed to assess antigen specifichuman IgG. Standard curves were generated using aliquots of the originaltest article. Antigen specific human IgG was determined as follows:ELISA (Nunc catalog number 44-2404-21) plates were coated overnight at4° C. with 1 μg/ml soluble BST1 Antigen-CFLIS in PBS (provided byAlere). Plates were washed and blocked with Superblock. After washingagain, standard curves and appropriately diluted samples were plated inPBS containing 2% FBS. After incubating for 1 hour at room temperature,the plates were washed. The detection antibody was anti-human kappaperoxidase conjugated goat polyclonal antibody (Millipore catalog numberA9502P, lot number NG1909833) at 1 in 5000 dilution in PBS plus 2% FBS.After washing, plates were developed with 1-Step Ultra TMB-ELISAsubstrate (Thermo Scientific catalog number 34028) and the reactionswere stopped with dilute sulfuric acid (98 g/L Ricca Chemical Companycatalog number 8140-16). The plates were read at 450 nm. The lowestdetectable level of human antigen specific IgG in the assay is 1.4ng/ml. The highest concentration of serum from the vehicle treatedanimals provided an ELISA reading similar to the blank control wells.The lowest concentration of human antigen specific IgG detected in theserum samples was about 340 ng/ml. The highest concentration of serumanalyzed was a 1 to 100 dilution of sample in ELISA assay buffer (or 1%final concentration of cynomolgus monkey serum).

Results

Two doses of BST1_A2_NF at 0.5, 5, and 20 mg/kg/dose (8 weeks apart) via15-minute intravenous infusion in female cynomolgus monkeys were welltolerated. There was no mortality or moribundity during the course ofthe study. There were no BST1_A2_NF-related changes on clinicalobservations, body weights, food consumption, clinical chemistry,coagulation, urinalysis, organ weights, bone marrow smear, macroscopicor microscopic evaluations.

The TK samples taken following the first dose of BST1_A2_NF yielded arange between 0.37 μg/ml to 624 μg/ml of antigen specific human IgG. Theconcentrations for the mg/kg group ranged from a low of undetectable formonkey 0901192 starting on Day 22 to a high of 624 μg/ml for monkey0902000 on Day 2. The 5 mg/kg group ranged between a high of 55 μg/ml onDay 1 to a low of 3.57 μg/ml on Day 43. The 0.5 mg/kg group ranged froma high of 4 μg/ml on Days 1 and 2 to a low of 0 to 0.37 μg/ml on Day 43(see FIG. 12 a). Following the second dose, the antigen specific humanIgG levels ranged from a low of undetectable 11 days post dose formonkey 0901192, to a high of 190.59 μg/ml on the second day after dosingfor monkey 0902000 in the 20 mg/kg group. For the 5 mg/kg group antigenspecific IgG levels ranged from a high of 42.60 μg/ml on Day 3, to a lowof 8.03 μg/ml on Day 14 (last day tested) after the second dose. The 0.5mg/kg group had antigen specific IgG levels ranging from 7.28 μg/ml onDay 1 to 0.65 μg/ml on Day 14 after the second dose (see FIG. 12 b).

SEQUENCE SUMMARY SEQ ID No Description Sequence 1 aa VH_A1MKQSTIALALLPLLFTPVAKAQVKLQQSGAELVRPGSSVKISCKASGYAFSNSWINWVKQRPGQGLEWIGQIYPGDYDTNYNGKFKGKATLTADYSSSTAYMQLNSLTSEDSAVYFCARGGSIYYGNLGFFDVWGAGTTVTVSSAKTTPPSVYPLAPGSAAQTNSMVTLGCLVKGYFPEPVTVTWNSGSLSSGVHTFPAVLQSDLYTLSSSVTVPSSTWPSETVTCNVAHP ASSTKVDKKIVPRDCHHHHHHH 2aa VH_A2 MKQSTIALALLPLLFTPVAKAQAYLQQSGPELVKAGASVKMSCKASGYSFIEYTINWVKQSHGKSLEWIGNIDPYYGTTYYNQMFTGKATLTVDQSSNTAYMQLKSLTSEDSAVYFCARGSAWFPYWGQGTLVTVSAAKTTPPSVYPLAPGSAAQTNSMVTLGCLVKGYFPEPVTVTWNSGSLSSGVHTFPAVLQSDLYTLSSSVTVPSSTWPSETVTCNVAHPASSTKVD KKIVPRDCHHHHHHH 3 aa VK_A1MKYLLPTAAAGLLLLAAQPAMAEMVLTQSPAIMSTSLGERVTMTCTASSRVSSSYLHWYQQKPGSSPKLWIYSTSNLASGVPARFSGSGSGTSYSLTISSMEAEDAATYYCHQYHRSPYTFGGGTKLEIKRADAAPTVSIFPPSSEQLTSGGASVVCFLNNFYPKDINVKWKIDGSERQNGVLNSWTDQDSKDSTYSMSSTLTLTKDEYERHNSYTCEATHKTSTSPIVKSFNR NES 4 aa VK_A2MKYLLPTAAAGLLLLAAQPAMADIVMSQSPAIMSASPGEKVTMTCSASSSVTYMYWYQQKPGSSPRLLIYDTSNLASGVPVRFSGSGSGTSYSLTISRMEAEDTATYYCQQWSNYPLTFGAGTKLELKRADAAPTVSIFPPSSEQLTSGGASVVCFLNNFYPKDINVKWKIDGSERQNGVLNSWTDQDSKDSTYSMSSTLTLTKDEYERHNSYTCEATHKTSTSPIVKSFNRNE S 5 nt VH_A1acgctttgtacatggagaaaataaagtgaaacaaagcactattgcactggcactcttaccgctcttatttacccctgtggcaaaagcccaggtgaagcttcagcagtccggggctgagctggtgaggcctgggtcctcagtgaagatttcctgcaaggcttctggctacgcattcagtaactcctggataaactgggtgaagcagaggcctggacagggtcttgagtggattggacagatttatcctggagattatgatactaactacaatggaaaattcaagggtaaagccacactgactgcagactactcctccagcacagcctacatgcagctcaacagcctaacatctgaggactctgcggtctatttctgtgcaagggggggatcgatctactatggtaacctcgggttcttcgatgtctggggcgcagggaccacggtcaccgtctcctcagccaaaacgacacccccatctgtctatccactggcccctggatctgctgcccaaactaactccatggtgaccctgggatgcctggtcaagggctatttccctgagccagtgacagtgacctggaactctggatccctgtccagcggtgtgcacaccttcccagctgtcctgcagtctgacctctacactctgagcagctcagtgactgtcccctccagcacctggcccagcgagaccgtcacctgcaacgttgcccacccggccagcagcaccaaggtggacaagaaaattgtgcccagggattgtcatcatcaccatcaccatcactaattgacagcttatcatcgatangct 6 nt VH_A2aaaaccctggcgttacccacgctttgtacatggagaaaataaagtgaaacaaagcactattgcactggcactcttaccgctcttatttacccctgtggcaaaagcccaggcttatctacagcagtctggacctgagctggtgaaggctggcgcttcagtgaagatgtcctgcaaggcttctggttactcattcattgagtacaccataaactgggtgaaacagagccatggaaagagccttgagtggattggaaatattgatccttattatggaaccacttattacaatcagatgttcacgggcaaggccacattgactgtagaccaatcttccaacactgcctacatgcagctcaagagcctgacatctgaggactctgcagtctatttctgtgcaagaggctccgcctggtttccttactggggccaggggactctagtcactgtctctgcagccaaaacgacacccccatctgtctatccactggcccctggatctgctgcccaaactaactccatggtgaccctgggatgcctggtcaagggctatttccctgagccagtgacagtgacctggaactctggatccctgtccagcggtgtgcacaccttcccagctgtcctgcagtctgacctctacactctgagcagctcagtgactgtcccctccagcacctggcccagcgagaccgtcacctgcaacgttgcccacccggccagcagcaccaaggtggacaagaaaattgtgcccagggattgtcatcatcaccatcaccatcactaattgacagctta tcatcgat7 nt VK_A1gtttttttggatggagtgaaacgatgaaatacctattgcctacggcagccgctggattgttattactcgctgcccaaccagccatggccgaaatggttctcacccagtctccagcaatcatgtctacatctctaggggaacgggtcaccatgacctgcactgccagctcacgtgtaagttccagttacttgcactggtaccagcagaagccaggatcctcccccaaactctggatttatagtacatccaacctggcttctggagtcccagctcgcttcagtggcagtgggtctgggacctcttactctctcacaatcagcagcatggaggctgaagatgctgccacttattactgccaccagtatcatcgttccccgtacacgttcggaggggggaccaagctggaaataaaacgggctgatgctgcaccaactgtatccatcttcccaccatccagtgagcagttaacatctggaggtgcctcagtcgtgtgcttcttgaacaacttctaccccaaagacatcaatgtcaagtggaagattgatggcagtgaacgacaaaatggcgtcctgaacagttggactgatcaggacagcaaagacagcacctacagcatgagcagcaccctcacgttgaccaaggacgagtatgaacgacataacagctatacctgtgaggccactcacaagacatcaacttcacccattgtcaagagcttcaacaggaatgagtcttaagtgattagctaattctagaacg 8 nt VK_A2actctctactgtttctccatacccgtttttttggatggagtgaaacgatgaaatacctattgcctacggcagccgctggattgttattactcgctgcccaaccagccatggccgacatcgttatgtctcagtctccagcaatcatgtctgcatctccaggggagaaggtcaccatgacctgcagtgccagctcaagtgtaacttacatgtactggtaccagcagaagccaggatcctcccccagactcctgatttatgacacatccaacctggcttctggagtccctgttcgcttcagtggcagtgggtctgggacctcttactctctcacaatcagccgaatggaggctgaagatactgccacttattactgccagcagtggagtaattacccactcacgttcggtgctgggaccaagctggagctgaaacgggctgatgctgcaccaactgtatccatcttcccaccatccagtgagcagttaacatctggaggtgcctcagtcgtgtgcttcttgaacaacttctaccccaaagacatcaatgtcaagtggaagattgatggcagtgaacgacaaaatggcgtcctgaacagttggactgatcaggacagcaaagacagcacctacagcatgagcagcaccctcacgttgaccaaggacgagtatgaacgacataacagctatacctgtgaggccactcacaagacatcaacttcacccattgtcaagagcttcaacaggaatgagtcttaagtgattagctaattctagaacgcgtcacttggcactggcc gtcgtttta9 aa VH_CDR1_A1 GYAFSNSWINW 10 aa VH_CDR1_A2 GYSFIEYTINW 11aa VH_CDR2_A1 GQIYPGDYDTNYNGKFK 12 aa VH_CDR2_A2 GNIDPYYGTTYYNQMFT 13aa VH_CDR3_A1 ARGGSIYYGNLGFFDV 14 aa VH_CDR3_A2 ARGSAWFPY 15aa VK_CDR1_A1 TASSRVSSSYLH 16 aa VK_CDR1_A2 SASSSVTYMY 17 aa VK_CDR2_A1STSNLAS 18 aa VK_CDR2_A2 DTSNLAS 19 aa VK_CDR3_A1 HQYHRSPYT 20aa VK_CDR3_A2 QQWSNYPLT 21 nt VH_CDRl_A1ggctacgcattcagtaactcctggataaactgg 22 nt VH_CDRl_A2ggttactcattcattgagtacaccataaactgg 23 nt VH_CDR2_A1ggacagatttatcctggagattatgatactaactacaatggaaaattcaag 24 nt VH_CDR2_A2ggaaatattgatccttattatggaaccacttattacaatcagatgttcacg 25 nt VH_CDR3_A1gcaagggggggatcgatctactatggtaacctcgggttcttcgatgtc 26 nt VH_CDR3_A2gcaagaggctccgcctggtttccttac 27 nt VK_CDRl_A1actgccagctcacgtgtaagttccagttacttgcac 28 nt VK_CDR1_A2agtgccagctcaagtgtaacttacatgtac 29 nt VK_CDR2_A1 agtacatccaacctggcttct 30nt VK_CDR2_A2 gacacatccaacctggcttct 31 nt VK_CDR3_A1caccagtatcatcgttccccgtacacg 32 nt VK_CDR3_A2 cagcagtggagtaattacccactcacg33 IGHV1-80*01 ggctacgcattcagtagctactggatgaactgg (Genebank:AC160990 Musmus) nt 138392-138424 34 IGHV1-80*01ggacagatttatcctggagatggtgatactaactacaacggaaagttcaag (Genebank:AC160990 Musmus) nt 138461-138511 35 IGHV1-39*01ggttactcattcactgactacaacatgaactgg (Genebank: AC079181 Musmus)nt 153362-153394 36 IGHV1-39*01ggagtaattaatcctaactatggtactactagctacaatcagaagttcaag (Genebank:AC079181 Musmus) nt 153431-153481 37 IGKV4-74*01actgccagctcaagtgtaagttccagttacttgcac (Genebank: AJ231217 Musmus)nt 496-531 38 IGKV4-74*01 agcacatccaacctggcttct (Genebank:AJ231217 Musmus) nt 577-597 39 IGKV4-74*01 caccagtatcatcgttccccaccca(Genebank: AJ231217 Musmus) nt 691-718 40 IGKV4-55*01agtgccagctcaagtgtaagttacatgtac (Genebank: AJ231225 Musmus) nt 523-552 41IGKV4-55*01 gacacatccaacctggcttct (Genebank: AJ231225 Musmus) nt 598-61842 IGKV4-55*01 cagcagtggagtagttacccaccca (Genebank: AJ231225 Musmus)nt 715-739 43 ADP-ribosyl cyclase MAAQGCAASRLLQLLLQLLLLLLLLAAGGARARWRGE2 (CD157; BST1) GTSAHLRDIFLGRCAEYRALLSPEQRNKNCTAIWEAFKVALDKDPCSVLPSDYDLFINLSRHSIPRDKSLFWENSHLLVNSFADNTRRFMPLSDVLYGRVADFLSWCRQKNDSGLDYQSCPTSEDCENNPVDSFWKRASIQYSKDSSGVIHVMLNGSEPTGAYPIKGFFADYEIPNLQKEKITRIEIWVMHEIGGPNVESCGEGSMKVLEKRLKDMGFQYSCINDYRPVKLLQCVDHSTHPDCALKSAAAATQRKAPSLYTEQRAGLIIPLFLVL ASRTQL 44 aa 29 - 292 of ADP-GARARWRGEGTSAHLRDIFLGRCAEYRALLSPEQRNKN ribosyl cyclase 2CTAIWEAFKVALDKDPCSVLPSDYDLFINLSRHSIPRDKS (CD157; BST1)LFWENSHLLVNSFADNTRRFMPLSDVLYGRVADFLSWCRQKNDSGLDYQSCPTSEDCENNPVDSFWKRASIQYSKDSSGVIHVMLNGSEPTGAYPIKGFFADYEIPNLQKEKITRIEIWVMHEIGGPNVESCGEGSMKVLEKRLKDMGFQYSCIND YRPVKLLQCVDHSTHPDCALKSAAAATQRK 45A2 VH (amino acids QAYLQQSGPELVKAGASVKMSCKASGYSFIEYTINWVK 21-137 SEQ IDQSHGKSLEWIGNIDPYYGTTYYNQMFTGKATLTVDQSS No: 2)NTAYMQLKSLTSEDSAVYFCARGSAWFPYWGQGTLVT VSA 46 VH1 - HumanisedQVQLVQSGA EVKKPGASVK VSCKASGYSF VH_A2 IEYTINWVRQ APGQGLEWIGNIDPYYGTTYYNQMFTGRATL TVDTSISTAY 47 BF238102 VHMELSRLRSDDTAVYYCARGSAWF PYWGQGTLV TVSS QVQLVQSGA EVKKPGASVK VSCKASGYSFTXXXXXWVRQ APGQGLEWMG XXXXXXXXXXX XXXXXXRVTL TRDTSISTAYMELSRLRSDDTAVYYCARXXXXX XXXWGQGTLV PVSS 48 A2 VL (amino acidsDIVMSQSPA IMSASPGEKV TMTCSAS-SS 22-128 SEQ IDVTYMYWYQQKPGSSPRLLIY DTSNLASGVP No: 4) VRFSGSGSGT SYSLTISRMEAEDTATYYCQQWSNYPLTFG AGTKLELK 49 VL1 - Humanised DIQMTQSPS SLSASVGDRV TITCSAS-SSVK_A2 VTYMYWYQQKPGKAPKLLIY DTSNLASGVP SRFSGSGSGT DYTLTISSLQPEDFATYYCQQWSNYPLTFG QGTKVEIK 50 X72441 VL DIQMTQSPS SLSASVGDRV TITCXXXXXXXXXXXWYQQKPGKAPKLLIY XXXXXXXGVP SRFSGSGSGT DFTLTISSLQPEDFATYYCXXXXXXXXXFG QGTKVEIK 51 VH1_CDR2 NIDPYYGTTYYNQMFQ 52 aa VH_A3MKQSTIALALLPLLFTPVAKAQVQLQQSRAELVMPGASVKMSCKTSGYTFSDYWVHWVRQRPGQGLEWIGAIDGSDTFNDYSQKFKGRATLTVDESSSTVYMQLSSLTSEDSAVYYCARGGLLQYWGQGTTLTVSSAKTTPPSVYPLAPGSAAQTNSMVTLGCLVKGYFPEPVTVTWNSGSLSSGVHTFPAVLQSDLYTLSSSVTVPSSTWPSETVTCNVAHPASSTKV DKKIVPRDCHHHHHHH 53 aa VK_A3MKYLLPTAAAGLLLLAAQPAMADIQLTQSPASLSASVGETVTITCRASENIYSYLAWYQQKQGKSPQLLVYNTKTLGEGVPSRFSGSGSGTQFSLKINSLQPEDFGSYYCQHHYGTPFTFGSGTKLEIKRADAAPTVSIFPPSSEQLTSGGASVVCFLNNFYPKDINVKWKIDGSERQNGVLNSWTDQDSKDSTYSMSSTLTLTKDEYERHNSYTCEATHKTSTSPIVKSFNRNES 54 nt VH_A3gtgaaacaaagcactattgcactggcactcttaccgctcttatttacccctgtggcaaaagcccaggtccagctgcagcagtctagggctgaacttgtgatgcctggggcttcagtgaagatgtcctgcaagacttctggctacacattctctgactactgggtacactgggtgaggcagaggcctggacaaggccttgagtggatcggagcgattgatggttctgatacttttaatgactacagtcagaagtttaagggcagggccacattgactgtagacgaatcctccagcacagtctacatgcaactcagcagcctgacatctgaggactctgcggtctattactgtgcaagggggggccttcttcagtactggggccaaggcaccactctcacagtctcctcagccaaaacgacacccccatctgtctatccactggcccctggatctgctgcccaaactaactccatggtgaccctgggatgcctggtcaagggctatttccctgagccagtgacagtgacctggaactctggatccctgtccagcggtgtgcacaccttcccagctgtcctgcagtctgacctctacactctgagcagctcagtgactgtcccctccagcacctggcccagcgagaccgtcacctgcaacgttgcccacccggccagcagcaccaaggtggacaagaaaattgtgcccagggattgtcatcatcaccatc accatcactaa55 nt VK_A3atgaaatacctattgcctacggcagccgctggattgttattactcgctgcccaaccagccatggccgacattcagctgacccagtctccagcctccctatctgcatctgtgggagaaactgtcaccatcacatgtcgagcaagtgaaaacatttacagttatttagcatggtatcagcagaaacagggaaaatctcctcagctcctggtctataatacaaaaaccttaggagaaggtgtgccatcaaggttcagtggcagtggatcgggcacacaattttctctgaagatcaacagcctgcagcctgaagattttgggagttattactgtcaacatcattatggtactccattcacgttcggctcggggacaaagttggaaataaaacgggctgatgctgcaccaactgtatccatcttcccaccatccagtgagcagttaacatctggaggtgcctcagtcgtgtgcttcttgaacaacttctaccccaaagacatcaatgtcaagtggaagattgatggcagtgaacgacaaaatggcgtcctgaacagttggactgatcaggacagcaaagacagcacctacagcatgagcagcaccctcacgttgaccaaggacgagtatgaacgacataacagctatacctgtgaggccactcacaagacatcaacttcacccattgtcaagagcttcaacaggaatgagtcttaa 56 aa VH_CDR1_A3 GYTFSDYWVHW57 aa VH_CDR2_A3 GAIDGSDTFNDYSQKFK 58 aa VH_CDR3_A3 ARGGLLQY 59aa VK_CDR1_A3 RASENIYSYLA 60 aa VK_CDR2_A3 NTKTLGE 61 aa VK_CDR3_A3QHHYGTPFT 62 nt VH_CDR1_A3 ggctacacattctctgactactgggtacactgg 63nt VH_CDR2_A3 ggagcgattgatggttctgatacttttaatgactacagtcagaagtttaag 64nt VH_CDR3_A3 gcaagggggggccttcttcagtac 65 nt VK_CDR1_A3cgagcaagtgaaaacatttacagttatttagca 66 nt VK_CDR2_A3 aatacaaaaaccttaggagaa67 nt VK_CDR3_A3 caacatcattatggtactccattcacg 68 IGHV1-69*01ggctacaccttcaccagctactggatgcactgg (AC073939) 69 IGHV1-69*01ggagagattgatccttctgatagttatactaactacaatcaaaagttcaag (AC073939) 70IGKV12-44*01 cgagcaagtgagaatatttacagttatttagca (AJ235955) 71IGKV12-44*01 aatgcaaaaaccttagcagaa (AJ235955) 72 IGKV12-44*01caacatcattatggtactcctcc (AJ235955)

The invention claimed is:
 1. An isolated antibody or antigen bindingfragment thereof that specifically binds to bone marrow stromal antigen1 (BST1), said antibody or antigen binding fragment thereof comprising:a) a heavy chain variable region comprising: i) a first vhCDR comprisingSEQ ID NO:10; ii) a second vhCDR comprising SEQ ID NO: 12 or SEQ ID NO:51; and iii) a third vhCDR comprising SEQ ID NO:14; and b) a light chainvariable region comprising: i) a first vlCDR comprising SEQ ID NO:16;ii) a second vlCDR comprising SEQ ID NO: 18; and iii) a third vlCDRcomprising SEQ ID NO:20.
 2. An antibody according to claim 1 comprising:a) a heavy chain variable region comprising SEQ ID NO: 46 and b) a lightchain variable region comprising SEQ ID NO:
 49. 3. The antibody orantigen-binding portion thereof, of claim 1, further comprising acovalently attached moiety.
 4. The antibody or antigen-binding portionthereof, of claim 3, wherein said moiety is a drug selected from thegroup consisting of a maytansinoid, a dolastatin, an auristatin, atrichothecene, a calicheamicin, CC1065 and derivatives thereof.
 5. Anisolated antibody or antigen binding fragment thereof that specificallybinds to bone marrow stromal antigen 1 (BST1), said antibody or antigenbinding fragment thereof comprising: a) a heavy chain variable regioncomprising SEQ ID NO: 2 and b) a light chain variable region comprisingSEQ ID NO:
 4. 6. An isolated monoclonal antibody, or an antigen bindingportion thereof, which competes for binding to BST1 with an antibody setforth in claim 1 or
 5. 7. The antibody of claim 1 or 5, wherein theantibody is of an IgG1 isotype.
 8. The antibody or antigen-bindingportion thereof, of claim 5, further comprising a covalently attachedmoiety.
 9. The antibody or antigen-binding portion thereof, of claim 8,wherein said moiety is a drug selected from the group consisting of amaytansinoid, a dolastatin, an auristatin, a trichothecene, acalicheamicin, CC1065 and derivatives thereof.
 10. An isolated antibodyor antigen binding fragment thereof that specifically binds to bonemarrow stromal antigen 1 (BST1), wherein said antibody or antigenbinding fragment thereof comprises heavy and light chain variableregions, and wherein the heavy chain variable region comprises SEQ IDNO:
 2. 11. An isolated antibody or antigen binding fragment thereof thatspecifically binds to bone marrow stromal antigen 1 (BST1), wherein saidantibody or antigen binding fragment thereof comprises heavy and lightchain variable regions, and wherein the light chain variable regioncomprises SEQ ID NO:
 4. 12. An isolated antibody or antigen bindingfragment thereof that specifically binds to bone marrow stromal antigen1 (BST1), wherein said antibody or antigen binding fragment thereofcomprises heavy and light chain variable regions, and wherein the heavychain variable region comprises SEQ ID NO:46.
 13. An isolated antibodyor antigen binding fragment thereof that specifically binds to bonemarrow stromal antigen 1 (BST1), wherein said antibody or antigenbinding fragment thereof comprises heavy and light chain variableregions, and wherein the light chain variable region comprises SEQ IDNO:
 49. 14. An isolated antibody or antigen binding fragment thereofthat specifically binds to bone marrow stromal antigen 1 (BST1), whereinsaid antibody or antigen binding fragment thereof comprises a heavychain variable region comprising SEQ ID NO: 46 and a light chainvariable region comprising SEQ ID NO: 49.